*\ 


INDUSTRIAL   CHEMISTRY 

BEING   A   SERIES   OF   VOLUMES   GIVING   A 
COMPREHENSIVE   SURVEY   OF 

THE    CHEMICAL    INDUSTRIES 

EDITED  BY  SAMUEL  RIDEAL,  D.Sc.  LOND,,  F.I.C. 

FELLOW  OF  UNIVERSITY  COLLEGE,   LONDON 

ASSISTED   BY 

JAMES  A.  AUDLEY,   B.Sc.,   F.I.C.        R.  S.  MORRELL,  M.A.,  PH.D. 
W.  BACON,  B.Sc.,  F.I.C.,  F.C.S.  J.  R.  PARTINGTON,  M.A.,  PH.D. 

E.DE  BARRY  BARNETT,  B.Sc.,A.I.C.    ARTHUR  E.  PRATT,  B.Sc.,Assoc.R.S.M. 
M.  BARROWCLIFF,  F.I.C.  ERIC  K.  RIDEAL,  M.A.,  PH.D.,  F.I.C. 

H.  GARNER  BENNETT,  M.Sc.  W.  H.  SIMMONS,  B.Sc.,  F.I.C. 

F.  H.  CARR,  F.I.C.  R.  W.  SINDALL,  F.C.S. 

S.  HOARE  COLLINS,  M.Sc.,  F.I.C.         D.  A.  SUTHERLAND,  F.I.C. 
H.  H.  GRAY,  B.Sc.  HUGH  S.  TAYLOR,  D.Sc. 

H.  C.  GREENWOOD,  D.Sc.  ARMAND  DE  WAELE,  B.Sc. 

C.  M.  WHITTAKER,  B.Sc. 
Stc.,  &c. 


EXPLOSIVES 


BY 

E.  DE  BARRY  BARNETT,  B.Sc.(LoND.),  A.I.C. 

CONSULTING  CHEMIST  AND   MANAGER  TO    BAGLBY,    MILLS  AND  CO.,   LTD.,    FORMERLY 

WORKS  CHEMIST,    NATIONAL  EXPLOSIVES   CO.,    LTD.,    AND    WORKS   MANAGER, 

STOCKTON-ON-TEES  CHEMICAL   WORKS,   LTD. 


NEW   YORK 
D.   VAN    NOSTRAND   COMPANY 

25   PARK  PLACE 
1919 


PRINTED  IN   GREAT  BRITAIN 


GENERAL    PREFACE 

THE  rapid  development  of  Applied  Chemistry  in  recent  years 
has  brought  about  a  revolution  in  all  branches  of  technology. 
This  growth  has  been  accelerated  during  the  war,  and  the 
British  Empire  has  now  an  opportunity  of  increasing  its 
industrial  output  by  the  application  of  this  knowledge  to  the 
raw  materials  available  in  the  different  parts  of  the  world. 
The  subject  in  this  series  of  handbooks  will  be  treated  from 
the  chemical  rather  than  the  engineering  standpoint.  The 
industrial  aspect  will  also  be  more  prominent  than  that  of 
the  laboratory.  Each  volume  will  be  complete  in  itself,  and 
will  give  a  general  survey  of  the  industry,  showing  how 
chemical  principles  have  been  applied  and  have  affected 
manufacture.  The  influence  of  new  inventions  on  the 
development  of  the  industry  will  be  shown,  as  also  the 
effect  of  industrial  requirements  in  stimulating  invention. 
Historical  notes  will  be  a  feature  in  dealing  with  the 
different  branches  of  the  subject,  but  they  will  be  kept 
within  moderate  limits.  Present  tendencies  and  possible 
future  developments  will  have  attention,  and  some  space 
will  be  devoted  to  a  comparison  of  industrial  methods  and 
progress  in  the  chief  producing  countries.  There  will  be  a 
general  bibliography,  and  also  a  select  bibliography  to  follow 
each  section.  Statistical  information  will  only  be  introduced 
in  so  far  as  it  serves  to  illustrate  the  line  of  argument. 

Each  book  will  be  divided  into  sections  instead  of 
chapters,  and  the  sections  will  deal  with  separate  branches 
of  the  subject  in  the  manner  of  a  special  article  or  mono- 
graph. An  attempt  will,  in  fact,  be  made  to  get  away  from 


434860 


vi  GENERAL  PREFACE 

the  orthodox  textbook  manner,  not  only  to  make  the  treat- 
ment original,  but  also  to  appeal  to  the  very  large  class  of 
readers  already  possessing  good  textbooks,  of  which  there 
are  quite  sufficient.  The  books  should  also  be  found  useful 
by  men  of  affairs  having  no  special  technical  knowledge,  but 
who  may  require  from  time  to  time  to  refer  to  technical 
matters  in  a  book  of  moderate  compass,  with  references  to 
the  large  standard  works  for  fuller  details  on  special  points 
if  required. 

To  the  advanced  student  the  books  should  be  especially 
valuable.  His  mind  is  often  crammed  with  the  hard  facts 
and  details  of  his  subject  which  crowd  out  the  power  of 
realizing  the  industry  as  a  whole.  These  books  are  intended 
to  remedy  such  a  state  of  affairs.  While  recapitulating  the 
essential  basic  facts,  they  will  aim  at  presenting  the  reality 
of  the  living  industry.  It  has  long  been  a  drawback  of  our 
technical  education  that  the  college  graduate,  on  commencing 
his  industrial  career,  is  positively  handicapped  by  his 
academic  knowledge  because  of  his  lack  of  information  on 
current  industrial  conditions.  A  book  giving  a  compre- 
hensive survey  of  the  industry  can  be  of  very  material 
assistance  to  the  student  as  an  adjunct  to  his  ordinary  text- 
books, and  this  is  one  of  the  chief  objects  of  the  present 
series.  Those  actually  engaged  in  the  industry  who  have 
specialized  in  rather  narrow  limits  will  probably  find  these 
books  more  readable  than  the  larger  textbooks  when  they 
wish  to  refresh  their  memories  in  regard  to  branches  of  the 
subject  with  which  they  are  not  immediately  concerned. 

The  volume  will  also  serve  as  a  guide  to  the  standard 
literature  of  the  subject,  and  prove  of  value  to  the  con- 
sultant, so  that,  having  obtained  a  comprehensive  view  of 
the  whole  industry,  he  can  go  at  once  to  the  proper 
authorities  for  more  elaborate  information  on  special  points, 
and  thus  save  a  couple  of  days  spent  in  hunting  through  the 
libraries  of  scientific  societies. 

As  far  as  this  country  is  concerned,  it  is  believed  that 
the  general  scheme  of  this  series  of  handbooks  is  unique, 
and  it  is  confidently  hoped  that  it  will  supply  mental 


GENERAL  PREFACE  vii 

munitions  for  the  coming  industrial  war.  I  have  been 
fortunate  in  securing  writers  for  the  different  volumes  who 
are  specially  connected  with  the  several  departments  of 
Industrial  Chemistry,  and  trust  that  the  whole  series  will 
contribute  to  the  further  development  of  applied  chemistry 
throughout  the  Empire. 

SAMUEIv 


PUBLISHERS'    NOTE 

We  much  regret  that,  owing  to  the  continued 
and  unexpected  increase  in  the  cost  of  printing 
since  the  Armistice,  it  has  been  found  impossible 
to  publish  future  volumes  in  the  f<  Industrial 
Chemistry  Series  "  at  the  price  originally  fixed 
°f  7/6  each-  If,  as  it  is  hoped,  prices  become 
more  reasonable,  we  propose  to  revert  as  nearly 
as  possible  to  the  earlier  arrangement. 


AUTHOR'S   PREFACE 

IN  the  following  pages  the  author  has  endeavoured  to  give 
a  clear  but  concise  account  of  the  manufacture  of  explosives, 
together  with  an  outline  of  the  methods  used  for  investi- 
gating this  class  of  substance.  The  explosives  industry  is 
an  important  one,  both  in  time  of  peace  and  in  time  of  war, 
and  is  intimately  bound  up  with  the  synthetic  dyestuff  and 
artificial  fertilizer  industries.  These  two  latter  industries 
are  on  the  point  of  being  established  on  what  one  trusts 
will  be  a  secure  basis  in  this  country,  and  probably  the 
explosives  industry  will  expand  with  them.  The  experience 
gained  by  the  troops  and  by  the  munition  workers  during 
the  war  in  the  handling  and  use  of  explosives  should  have 
largely  removed  the  distrust  in  which  these  bodies  are 
usually  held,  and  at  the  same  time  have  demonstrated  their 
manifold  uses.  It  is  certain  that  prior  to  the  war  the  use 
of  explosives  in  this  country  was  far  too  restricted,  only 
small  quantities  being  used  for  agricultural  purposes,  such 
as  breaking  up  subsoil,  drainage,  etc.  In  the  future  it  is 
hoped  that  they  will  be  more  extensively  used  for  general 
purposes,  and  this  will  no  doubt  prove  to  be  the  case  if  they 
are  made  available  at  a  low  price.  The  enormous  nitrating 
plants  established  for  war  purposes  and  the  advent  of 
synthetic  ammonium  nitrate  should  render  this  possible 
with  nitrate  of  ammonia  explosives.  The  author  has 
devoted  a  special  section  to  Coal  Mine  Explosives,  as  the 
importance  of  the  subject  seems  to  warrant  special  treat- 
ment. It  is  hoped  that  the  British  Government  will  divert 
some  of  the  money  that  is  to  be  expended  on  "Scientific 
Research  "  to  the  investigation  of  shot  firing  in  coal  mines, 


x  AUTHOR'S  PREFACE 

as  up  to  the  present  they  seem  to  have  rested  content  with 
carrying  out  the  official  tests.  It  is  rather  depressing  to 
find  that,  in  spite  of  our  enormous  coal  fields,  we  carry  out 
less  work  on  coal  mine  explosives  than  any  of  the  important 
coal -getting  countries  in  either  hemisphere.  There  seems 
to  be  no  British  publication  analogous  to  the  excellent 
"  Bulletins  of  the  U.S.  Bureau  of  Mines  "  or  the  "  Bulletins 
of  the  U.S.  Bureau  of  Explosives/' 

The  author  wishes  to  acknowledge  his  indebtedness  to 
C.  A.  Marshall's  invaluable  work  "  Explosives  ;  their  History, 
Manufacture,  Properties  and  Uses,"  in  which  the  industry 
is  treated  in  far  greater  detail  than  is  possible  in  a  volume 
of  this  size. 

E.   DE   BARRY   BARNETT. 

June,  1919. 


CONTENTS 


PACK 

GENERAL  PREFACE      v 

AUTHOR'S   PREFACE .       ix 

ABBREVIATIONS    .  ...  .       xv 


INTRODUCTION 

Historical  Sketch.    Explosives  Act,  1875.    Buildings  and  Safety.     Imports 

and  Consumption.     Official  Classification.     Bibliography         .         .         i 


SECTION   I.-GUNPOWDER 

Composition.  First  Mixing.  Incorporating  or  Milling.  Pressing.  Granu- 
lating or  Corning.  Glazing.  Stoving  or  Drying.  Blending. 
Moulding.  Sodium  Nitrate  Powders.  Sprengsalpeter.  Bobbinite. 
Stability,  etc.  Literature 17 


SECTION   II.—  EXPLOSIVE   COMPOUNDS 

Nitroglycerine.  Nitrating  House.  Separating  House.  Wash  and 

Filter  House.  After-Separation.  Nitrator-Separator  «  .  .  31 

Nitrocellulose.  Guncotton.  Abel  Process.  Direct  Dipping  Process. 
Displacement  Process.  Nitrating  Centrifugals.  Collodion.  Wash- 
ing. Pulping  ..........  43 

Nitroaromatic  Compounds.  Dinitrobenzole.  Dinitrotoluol.  Trinitro- 
toluol. Picric  Acid.  Tetranitroaniline.  Tetranitromethylaniline  .  52 

Miscellaneous  Compounds.  Nitromethane.  Tet  rani  t  torn  ethane.  Nitro- 
sugars.  Nitro-mannitol.  Nitro-starch.  Hexanitrodiphenylamine. 
Hexanitrodiphenyl  Sulphide.  Hexanitrodiphenyl  Oxide.  Hexanitro- 
oxanilide.  Hexanitrodiphenyl  .......  61 

Spent  Acids.    Literature        .........       64 


xii  CONTENTS 

SECTION   III.— SMOKELESS   PROPELLANTS 

PROPELLANTS  FOR  RIFLED  ARMS. 

PAGE 

Nitroglycerine  Propellants,    Ballistite.    Cordite  Mark  I.    Cordite  M.D. 

Filite.    Solenite.     Wiirfelpulver.     Rohrenpulver.     Axite.    Moddite  .       72 
Nitrocellulose  Propellants.    U.S.  Military  Powder.    Poudre  B     .        -79 

PROPELLANTS  FOR   SHOT  GUNS 

33-grain  Powders.  42-grain  Powders.  Schultze  Powder.  Amberite. 
E.G.  Powder.  Smokeless  Diamond.  Poudre  S.  Poudre  J, 
Poudre  M.  Poudre  T.  Mullerite.  Fasan.  Tiger.  Rothweil. 
Walsrode.  Adler-Marke 82 

Aliphatic  Solvents.     Literature 87 


SECTION   IV.— BLASTING  EXPLOSIVES 

Dynamite  and   its  Congeners.     Dynamite  No.  I.     Dynamite  No.  2. 

Dynamite  No.  3.      Giant   Powder.      French   Dynamites.      Carbo- 

dynamite.      American  Straight  Dynamites.      Ammonia  Dynamite. 

Judson  Powder.  Vulcan  Powder.  Stump  Powder.  Low  Powder  .  93 
Gelatinized  Explosives.  Blasting  Gelatine.  Gelatine  Dynamite. 

Gelignite.  American  Gelatins.  French  Gommes.  Forcite  .  .  99 
Chlorate  and  Perchlorate  Mixtures.  Sprengel  Explosives.  Promethee. 

Rack-a-Rock.       Liquid    Air    Explosives.       Cheddite.        Steelite. 

Yonckite.  Blastine.  Pernitral i°6 

Ammonium  Nitrate  Explosives.  Astralit.  Fulmenit.  Ammonal. 

Gesteins-Westfalit IX3 

Tonite.  Literature  .  .  •  •  !I5 


SECTION   V— SAFETY   COAL  MINE 
EXPLOSIVES 

Duration  of  Flame.  Test  Galleries.  German  Gallery.  Austrian  Gallery. 
Belgian  Gallery.  French  Gallery.  U.S.  Gallery.  British  Gallery. 
Rotherham  Test.  British  Permitted  Explosives.  Bobbinite.  German 
Explosives.  Austrian  Explosives.  Belgian  Explosifs  S.G.P. 
French  Explosifs  de  Surete.  Literature  .  .  .  .  •  117 


SECTION   VI.— PERCUSSION   CAPS, 
DETONATORS   AND   FUZES 

Caps  and  Detonators.  Mercury  Fulminate.  Lead  Azide.  Percussion 
Caps.  Wet  Mixing.  Dry  Mixing.  Jelly  Bag.  Triplex  Safety  Glass. 
Cap  Filling.  Detonators.  Composite  Detonators.  Sizes  of  Deto- 
nators. Filling  Detonators,  Testing  Detonators.  Electric  Detonators  143 

Fuzes.  Safety  Fuze.  Instantaneous  Fuze.  Quick-Match.  Slow-Match. 

Detonating  Fuze.  Shell  Fuzes 156 

Literature .....     160 


CONTENTS  xiii 

SECTION  VI.— MATCHES,  PYROPHORIC 
ALLOYS   AND   PYROTECHNY 

PAGE 

Matches 162 

Pyrophoric  Alloys 168 

Pyrotechny         ...                  170 

Literature    ............  177 


SECTION  VIII.— EXPLOSIVE   PROPERTIES 

Power  and  Brisance.  Trauzl  Lead  Block.  Mortar.  Ballistic  Pendulum. 

Brisance  Meter  .  .  . 178 

Velocity  of  Detonation.  Mettegang  Recorder.  Dautrich's  Method. 
Influence  of  Diameter  and  Density.  Nitroglycerine.  American 
Straight  Dynamites.  Gelatinized  Explosives  and  Ammonia  Dyna- 
mites. Tables 185 

Pressure,  Heat  and  Temperature.  Rodman  Gauge.  Crusher  Gauge. 
Bichel  Recorder.  Peteval  Recorder.  Bombs  and  Bomb-Calorimeters. 
Calculation  of  Temperature .  .......  195 

Chronography.  Internal  and  External  Ballistics.  Le  Boulange  Chrono- 
graph. Klepsydra.  Bashforth  Chronograph.  Schultze-Marcel- 
Dieprez  Chronograph.  Mahieu  Chronograph  ....  202 

Literature    ....  .,..,...     205 


SECTION    IX.— SENSITIVENESS   AND 
STABILITY 

Mechanical  Shock.  Detonation.  Influence.  Heat  and  Ignition.  Incor- 
poration. Deliquescence.  Exudation.  Abel  Heat  Test.  Guttmann 
Test.  Moir  Test.  Spica  Test.  Vieille  Test.  Waltham  Abbey 
Silvered  Vessel  Test.  German  135°  C.  Test.  Will  Test  .  .  207 

Literature 225 

CONCLUSION  .  227 

INDEX      .  235 


ABBREVIATIONS 

* 

LITERATURE 

A.  Annalen  der  Chemte. 
A.E.     Arms  and  Explosives. 

A.R.    Annual  Report  of  H.M.  Inspector  of  Explosives. 

B.  Berichte  des  Deutschen  Chemischen  Gesellschaft. 
C.r.     Comptes  r endues. 

J.S.  C.  1,    Journal  of  the  Society  of  Chemical  Industry. 

P.S.    Memorial  des  Poudres  et  Salpetres. 

Soc.     Transactions  of  the  Chemical  Society. 

S.R.     Special  Report  by  H.M.  Inspector  of  Explosives. 

S.S.    Zeitschrift  f.  Gesamte  Schiess — u.  Sprengstoff  Wesen. 

D.R.P.    Deutsches  Reichs  Patent. 

A. P.     American  Patent. 

E.P.     English  Patent. 

F.P.    French  Patent. 

COMPOUNDS,  ETC. 

The  following  abbreviations,  which  are  current  in  all  explosives  works  in 
Great  Britain,  are  used  throughout  the  text : — 

E.G.    Blasting  Gelatine.  M.N.N.    Mononitronaphthalene. 

C.C.    Collodion  Cotton.  M.N.T.    Mononitrotoluol. 

D.N.B.    Dinitrobenzole.  N.C.    Nitrocellulose. 

D.N.N.    Dinitronaphthalene.  N.G.    Nitroglycerine. 

D.N.T.     Dinitrotoluol.  P.A.     Picric  Acid. 

G.C.     Guncotton.  T.N.A.    Tetranitroaniline. 

G.P.     Gunpowder.  T.N.N.    Trinitronaphthalene. 

MJ.     Mineral  Jelly.  T.N.T.    Trinitrotoluol. 

M.N.B.     Mononitrobenzole.  W.M.     Wood  Meal. 

M.A.  is  mixed  acid  (nitric  and  sulphuric)  and  N.A.  nitric  acid  of  any  strength, 
the  monohydrate  being  denoted  by  its  chemical  formula,  HNO3.  S.A.  is  sul- 
phuric acid  of  any  strength,  the  commercial  concentrated  acid  (168°  Tw.)  being 
denoted  by  C.O.V.  (concentrated  oil  of  vitriol),  D.O.V.  (double  oil  of  vitriol)  or 
R.O.V.  (rectified  oil  of  vitriol).  The  monohydrate  is  denoted  by  its  chemical 
formula,  H2SO4.  The  fuming  acid  is  known  as  "  oleum,"  or  much  less  frequently 
as  F.O.V.  or  N.O.  V.  (fuming  oil  of  vitriol,  Nordhausen  oil  of  vitriol). 


EXPLOSIVES 


INTRODUCTION 

Historical  Sketch. — The  origin  of  gunpowder,  which  was 
the  only  explosive  known  until  the  middle  of  the  nine- 
teenth century,  is  uncertain.  Some  authors  regard  Greek 
Fire,  rather  extensively  used  in  the  defence  of  Constanti- 
nople in  the  seventh  century,  as  a  form  of  gunpowder, 
but  it  seems  reasonably  certain  that  this  was  merely  an 
incendiary  mixture  to  which  crude  nitre  may  or  may  not 
have  been  added  in  order  to  make  it  burn  more  fiercely. 
The  Chinese  seem  to  have  made  use  of  gunpowder  in  war- 
fare about  1232,  and  the  writings  of  Roger  Bacon  contain 
directions  for  the  purification  of  nitre  and  anagrams  and 
cryptograms  which  appear  to  describe  the  preparation  of 
gunpowder,  although  some  doubt  has  been  cast  on  their 
authenticity.  His  later  works,  however,  notably  "  Opus 
Tertium,"  "  De  Secretis,"  and  "Opus  Magnus,"  leave  no 
doubt  that  he  was  acquainted  with  explosive  mixtures  of 
sulphur,  charcoal,  and  nitre.  About  this  period  also,  the 
Arabs  seem  to  have  had  knowledge  of  the  explosive  pro- 
perties of  similar  mixtures. 

The  early  uses  of  gunpowder  were  confined  to  warfare, 
and  no  use  seems  to  have  been  made  of  it  for  blasting 
purposes  for  several  hundred  years.  It  was  originally  used 
in  the  form  of  crude  hand  grenades,  and  probably  was  at 
first  of  most  use  in  striking  terror  into  the  enemy.  Cannon 
were  first  used  by  the  English  in  1346  at  the  battle  of 
Crecy,  but  seem  to  have  been  used  a  few  years  prior  to 
this  in  the  Hispano-Moorish  wars. 

manufacture  of  gunpowder  was  originally  carried 


-EXPLOSIVES 

out  by  the  very  crude  method  of  pounding  the  ingredients 
together  by  hand  in  mortars,  but  edge  runners  were  intro- 
duced towards  the  end  of  the  sixteenth  century.  The 
original  mixtures  were  of  very  fine  grain,  were  deliquescent, 
and  the  ingredients  separated  very  easily  when  the  powder 
suffered  vibration  as  in  transport.  In  the  fourteenth 
century  attempts  were  made  to  avoid  this  latter  defect  by 
the  addition  of  camphor,  sal-ammoniac  and  gum,  and  in 
the  sixteenth  century  the  process  of  "  corning  "  or  "  granu- 
lating "  was  introduced.  This  was  done  by  moistening 
the  powder  during  the  latter  stages  of  mixing,  so  as  to  obtain 
a  cake  which  was  subsequently  broken  up  and  sifted. 

Fuzed  shell  were  first  introduced  in  1588,  but  the  fuzes 
were  naturally  of  a  very  crude  nature.  More  accurate 
fuzes  were  employed  by  the  British  at  the  siege  of  Gib- 
raltar in  1779,  and  shrapnel  shell  was  introduced  a  few 
years  later. 

Berthollet,  as  a  result  of  his  researches  on  chlorates,  in 
1788  suggested  substituting  potassium  chlorate  for  nitre, 
and  obtained  a  more  powerful  explosive  by  this  means, 
but  it  was  too  dangerous  to  make  or  use.  A  chlorate  powder, 
however,  was  adopted  in  1805  by  Forsyth  as  a  priming 
charge. 

Fulminate  caps  seem  to  have  come  into  use  first  about 
1815,  and  in  1831  Bickford  first  introduced  safety  fuze. 
The  discovery  of  guncotton  by  Schonbein  in  1845,  and  of 
nitroglycerine  by  Sobrero  in  1846,  opened  up  new  fields, 
although  the  accidents  attendant  on  the  manufacture  of 
these  substances  at  first  greatly  delayed  their  general  intro- 
duction. Schonbein  sold  the  British  rights  of  his  patent 
to  John  Hall  and  Sons,  of  Faversham,  who  manufactured 
guncotton  for  a  few  months,  but  abandoned  it  in  1847, 
after  a  disastrous  explosion.  Six  years  later  the  Austrian 
Government  took  up  the  matter,  and  General  von  I,enk 
constructed  some  batteries  in  which  guncotton  was  used 
both  as  a  propellant  and  as  a  bursting  charge  for  the  shell. 
These  were  not  an  unmitigated  success,  and  after  two 
disastrous  explosions  in  1865,  they  were  abandoned./ 

^ 


INTRODUCTION  3 

In  the  meantime  the  British  Government  had  taken 
up  the  subject,  and  Frederick  Abel  carried  out  investiga- 
tions on  their  behalf.  He  quickly  realized  that  the  insta- 
bility of  guncotton  was  due  to  the  difficulty  in  washing  it, 
and  in  1865  introduced  the  pulping  process.  Simple  as  it 
may  seem,  this  must  be  regarded  as  an  epoch-making  dis- 
covery, as  it  at  once  changed  a  very  dangerous  process  into 
one  of  the  safest  known  in  an  explosives  works.  Also  the 
wet  pulp  could  be  compressed  into  blocks  which  were 
convenient  for  transport  and  use.  The  usefulness  of  these 
blocks  was  greatly  enhanced  by  the  discovery  by  Braun 
in  1868  that  dry  guncotton  could  be  fired  by  a  fulminate 
detonator,  and  that  wet  guncotton  could  be  fired  in  the  same 
way  if  a  small  primer  of  dry  guncotton  was  used.  The 
value  of  this  discovery  will  be  realized  when  it  is  remem- 
bered that  wet  guncotton  is  non-inflammable  and  in- 
sensitive to  shock.  These  slabs  of  wet  guncotton  have  for 
many  years  been  the  standard  explosive  for  military  demoli- 
tions and  for  signal  maroons,  and  until  quite  recently  have 
been  the  invariable  charge  for  torpedoes. 

As  stated  above,  nitroglycerine  was  discovered  in  1846 
by  Sobrero,  who,  however,  does  not  seem  to  have  attached 
any  importance  to  the  discovery,  and  it  was  not  until  Alfred 
Nobel  took  up  the  subject  in  1862  that  any  attempt  was  made 
to  employ  it  as  an  explosive.  In  this  year  Nobel  commenced 
its  manufacture  near  Stockholm  in  Sweden,  but  the  numerous 
accidents  that  accompanied  its  use  soon  led  to  its  prohibi- 
tion by  all  countries.  Nobel  then  sought  for  a  means  of 
rendering  it  more  safe,  and  discovered  in  1867  that  this 
could  be  done  by  absorbing  it  in  some  porous  material. 
The  most  suitable  material  of  this  nature  was  found  to  be 
kieselguhr,  good  qualities  of  which  will  take  up  three  times 
their  weight  of  nitroglycerine  and  still  remain  dry,  although 
Nobel  also  patented  the  use  of  other  porous  materials,  such 
as  brick  dust,  plaster,  etc. 

A  great  advance  was  made  in  1875,  when  Nobel  intro- 
duced his  first  gelatinous  explosive.  The  discovery  of  this 
is  said  to  have  been  due  to  an  accident,  Nobel  having  used 


4  EXPLOSIVES 

collodion  solution  to  close  a  cut  in  his  hand  and  then  having 
noticed  that  this  formed  a  jelly  with  the  nitroglycerine  with 
which  he  was  carrying  out  some  experiments  later  in  the 
day.  The  first  explosive  of  this  nature,  Blasting  Gelatine, 
contained  about  92  per  cent,  of  nitroglycerine  and  8  per 
cent,  of  collodion  cotton.  It  experienced  an  immediate 
success,  but  a  demand  at  once  arose  for  less  violent  and 
less  brisant  explosives  of  the  same  nature.  These  were 
readily  made  by,  preparing  a  thinner  jelly  and  then  doping 
with  potassium  nitrate  and  wood  meal.  Mixtures  of  this 
nature  have  met  with  very  wide  use  under  the  names  of 
Gelatine  Dynamite  and  Gelignite,  Gelatine  Dynamite  being 
stronger  than  Gelignite,  but  not  so  strong  as  Blasting 
Gelatine. 

A  new  class  of  explosive  was  introduced  by  Sprengel 
in    1871.     He    found    that    mixtures    of    suitable    organic 
matter,  such  as  nitrobenzole,  and  strong  or  fuming  nitric 
acid    or   liquid    nitrogen    tetr oxide,    could   be    detonated. 
These  had  the  advantage  that  the  ingredients  were  kept 
•  separate  and  only  mixed  just  before  the  shot  was  fired,  and 
although  nitric  acid  is  an  inconvenient  liquid  to  transport, 
Sprengel  explosives  enjoyed  some  vogue.     A  more  rational 
explosive  of  the  Sprengel  class  was  introduced  by  Devine  in 
1880.     This  consisted  in  a  cartridge  of  potassium  chlorate 
which  immediately  before  use  was  dipped  into  an  organic 
liquid  such  as  nitrobenzole.     Rock-a-rock  was  an  explosive 
of  this  nature,  and  was  used  in  1885  for  blasting  Hell  Gate 
Rock  in  New  York  harbour.     The  first  ammonium  nitrate 
explosive  was  introduced  by  Favier  in  1885,  but  attracted 
scant  attention  at  the  time  on  account  of  its  objectionable 
hygroscopic  properties.     Finally,  in  recent  years  proposals 
have  been  made  to  employ  mixtures  of  liquid  air  or  oxygen 
in  conjunction  with  organic  matter,  and  although  a  good 
deal  of  the  blasting  in  connection  with  the  Simplon  tunnel 
was  carried  out  with  explosives  of  this  class,  they  suffer 
from  obvious  disadvantages  and  are  never  likely  to  come 
into    general    use.     They   have  been   used,   however,   for 
general   blasting   purposes    in   Germany   during  the   war. 


INTRODUCTION  5 

It  may  be  mentioned  that  explosives  of  the  Sprengel  class 
have  never  been  used  in  this  country,  as  mixing  the  in- 
gredients is  regarded  as  a  process  of  manufacture  within  the 
meaning  of  the  Act,  and  as  such  can  only  be  carried  on  on 
licensed  premises  (Explosives  Act,  1875). 

As  stated  on  page  2,  Berthollet  in  1788  was  the  first  to 
propose  the  use  of  chlorates,  but  was  compelled  to  abandon 
the  scheme  on  account  of  the  great  sensitiveness  of  his 
mixtures.  This  danger  was  remedied  by  Street  in  1897,  who 
prepared  safe  chlorate  mixtures  from  potassium  chlorate  and 
castor  oil  thickened  with  a  nitrohydrocarbon.  These  have 
met  with  considerable  success  under  the  name  of  Cheddite. 

The  first  smokeless  powder  after  von  I,enk's  nitrocotton 
batteries  was  introduced  by  Schultze  in  1865.  It  con- 
sisted of  pellets  of  wood  which  were  nitrated  and  then 
impregnated  with  barium  nitrate  and/or  potassium  nitrate. 
A  great  stride  was  made  by  Volkmann  five  years  later,  who 
partly  gelatinized  nitrated  wood  by  treatment  with  a  mixture 
of  alcohol  and  ether.  This  must  be  regarded  as  having  laid 
the  foundation  of  the  modern  smokeless  powder  industry. 
A  similar  powder,  B.C.  Powder,  was  introduced  in  1882 
by  the  Explosives  Company  of  Stowmarket.  It  consisted 
of  partly  gelatinized  nitrocotton  impregnated  with  a  mixture 
of  barium  and  potassium  nitrates,  and  found  immediate 
favour  among  sportsmen. 

The  first  smokeless  military  powder  was  Poudre  B, 
introduced  by  Vielle  in  1886,  and  adopted  by  the  French 
Government.  It  was  made  by  forming  a  dough  of  nitro- 
cellulose with  alcohol  and  ether,  which  was  then  rolled  out 
into  sheets,  cut  up  into  strips,  and  dried. 

Two  years  later  Nobel  introduced  Ballistite,  made  by 
gelatinizing  soluble  nitrocellulose  with  nitroglycerine,  and 
in  the  same  year  the  British  Government  introduced  Cordite, 
made  by  gelatinizing  guncotton  with  nitroglycerine  and 
acetone.  These  rival  discoveries  led  to  a  lawsuit,  the  issue 
of  which  turned  on  the  definition  of  nitrocellulose. 

Sprengel  in  1871  drew  attention  to  the  fact  that  picric 
acid   could  be  detonated,   but  no   use  was   made  of  this 


6  EXPLOSIVES 

discovery  until  Turpin  proposed  its  use  in  1886  as  a  bursting 
charge  for  shells.  For  this  purpose  it  found  wide  application 
under  the  names  of  Melinite,  L,yddite,  etc.,  but  has  now  been 
largely  replaced  by  the  cheaper  and  safer  trinitrotoluol. 

Tetranitroaniline  and  tetranitromethyl  aniline  were  dis- 
covered by  Flursheim  in  1910,  but  at  present  their  cost 
of  manufacture  precludes  their  use  except  in  detonators, 
in  which  they  are  likely  to  find  extensive  employment. 

The  general  introduction  of  explosives  for  blasting 
purposes  led  to  a  considerable  increase  in  coal-mine  accidents, 
due  to  the  shot  firing  the  mine  gases  or  causing  a  dust 
explosion.  Macnab  in  1873  first  suggested  remedying  this 
by  placing  a  cylinder  of  water  in  front  of  the  charge,  and  this 
was  shortly  followed  by  suggestions  involving  the  employ- 
ment of  jellies  containing  90  per  cent,  of  water,  wet  moss 
or  salts  rich  in  water  of  crystallization  in  the  same  way. 
None  of  these  were  altogether  successful,  but  the  setting 
up  of  experimental  galleries  in  1885  by  the  Prussian  and 
other  governments  soon  led  to  the  discovery  that  as  a  rule 
ammonium  nitrate  explosives  are  the  safest  to  use  in  fiery 
mines.  The  conditions  which  must  be  fulfilled  by  an  ex- 
plosive for  use  in  fiery  mines  are  now  stringent,  and  in  order 
to  fulfil  them  it  is  necessary  to  add  a  considerable  amount 
of  an  inactive  salt  to  the  explosive.  It  was  not  until  1913 
that  a  gelatinous  explosive  was  discovered  which  would 
pass  the  Rotherham  test,  in  which  year  Messrs.  Curtis  and 
Harvey,  I/td.,  patented  Super- Rippite. 

Explosives  Act,  1875.— The  Explosives  Act,  1875,  is 
entitled  "  An  Act  to  amend  the  law  with  respect  to  manu- 
facturing, keeping,  selling,  carrying  and  importing  gun- 
powder, nitroglycerine  and  other  explosive  substances/' 
The  third  section  of  the  Act  defines  an  explosive  as  "  .  .  . 
gunpowder,  nitroglycerine,  blasting  powders,  fulminate  of 
mercury  or  of  other  metals,  coloured  fires,  and  every  other 
substance,  whether  similar  to  those  above  mentioned  or  not, 
used  or  manufactured  with  a  view  to  produce  a  practical 
eff ect  by  explosion  or  a  pyrotechnic  effect ;  and  includes  fog- 
signals,  fireworks,  fuzes,  rockets,  percussion  caps,  detonators, 


INTRODUCTION  7 

cartridges,  ammunition  of  all  descriptions,  and  every  adop- 
tion or  preparation  of  an  explosive  as  so  defined."  Section 
104  of  the  Act  gives  power  to  include  any  specially  dangerous 
substance  even  if  not  manufactured  or  used  "  to  produce 
a  practical  effect  by  explosion/'  Acetylene,  for  example, 
under  certain  conditions  is  included  under  the  Act.  The 
Explosives  Act  prohibits  the  manufacture  of  any  explosive 
on  any  premises  not  duly  licensed,  fixes  the  minimum  dis- 
tance of  such  premises  from  private  dwellings,  public  roads, 
etc.,  and  establishes  procedure  for  granting  such  licences. 
It  provides  safeguards  for  workers,  insists  that  each  separate 
building  in  a  factory  shall  be  separately  licensed  and  the 
amount  of  explosive  and  the  number  of  workers  in  it  at  any 
time  limited.  It  prohibits  certain  dangerous  processes  and 
mixtures,  such  as  mixtures  of  chlorates  and  sulphur,  and 
endows  the  inspectors  under  the  Act  with  wide  powers. 
The  Act  must  be  regarded  as  a  very  fair  one,  and  is  ad- 
ministered with  extremely  little  friction  in  view  of  the 
stringency  of  its  provisos. 

Buildings  and  Safety. — Owing  to  the  dangerous  nature 
of  the  material  handled,  manufacturing  operations  are 
carried  out  in  a  series  of  small  separate  huts,  the  number  of 
workers  in  any  hut  rarely  exceeding  five,  although  in  some 
of  the  less  dangerous  processes  this  number  may  be  exceeded. 
The  danger  buildings  in  an  explosives  factory  can  be  roughly 
divided  into  two  classes,  viz.  (a)  magazines  used  for  storing 
explosives,  and  (b)  buildings  used  for  manufacturing  purposes. 
The  former  of  these  should  be  of  strong  construction,  so  as 
to  prevent  the  entrance  of  any  unauthorized  person.  They 
are  usually  built  of  stone  or  brick,  with  double  doors,  the 
outer  door  generally  being  sheathed  in  iron.  Working 
buildings,  on  the  other  hand,  should  be  of  as  light  and 
flimsy  a  character  as  possible,  so  that  in  case  of  an  explosion 
heavy  debris  is  not  thrown  about.  They  are  usually 
constructed  of  light  matchboard,  the  roof  being  of  the  same 
material  and  covered  with  some  non-inflammable  sheet. 
A  light,  ferroconcrete  construction  has  been  proposed  as 
suitable  for  danger  buildings,  as  it  has  been  urged  that  an 


S  EXPLOSIVES 

explosion  would  reduce  it  to  powder,  but  the  suggestion  has 
not  been  adopted. 

All  danger  buildings  must  be  surrounded  by  an  earth 
mound  reaching  to  the  roof,  so  as  to  deflect  the  explosive 
wave  upwards  in  case  of  an  explosion.  The  entrance 
through  the  mound  should  be  directly  opposite  the  door  of 
the  building  when  possible.  The  floors  of  danger  buildings 
are  usually  covered  with  oilcloth,  or  in  some  cases  with 
sheet  lead.  They  must  be  washed  thoroughly  every  day, 
and  when  dusty  material  such  as  dry  guncotton  is  being 
dealt  with  must  be  kept  wet  while  work  is  being  carried  on. 
All  windows  must  be  made  of  frosted  glass  so  as  to  exclude 
direct  sunlight,  and  all  doors  must  open  outwards.  Further, 
the  doors  must  be  provided  with  a  brass  lock  and  key,  for 
securing  them  when  work  is  not  being  carried  on,  but  when 
occupied  by  workers  must  be  closed  only  by  a  spring  catch, 
so  that  they  can  be  opened  by  a  push  in  case  of  emergency. 
The  brass  work  must  either  be  kept  bright  or  painted  over. 
Artificial  light  when  required  is  provided  by  incandescent 
electric  lamps.  These  are  enclosed  in  a  glass  bell  and  then 
set  in  recesses  in  the  walls,  and  separated  from  the  inside  of 
the  building  by  a  thick  plate  of  glass.  All  switches,  etc., 
must  be  external  to  the  building.  All  workers  must  wear 
special  clothes  made  of  wool  and  without  pockets,  and  must 
carry  with  them  no  metallic  articles,  such  as  metal  buttons, 
jewellery,  etc.,  nor  any  smoking  materials  or  matches. 
Danger  buildings  are  all  "  clean  "  buildings,  and  must  not 
be  entered  unless  the  person  entering  dons  special  shoes. 
Workers  usually  wear  slippers  without  nails,  felt  slippers 
or  rubber  boots.  These  are  kept  in  a  cupboard  in  the  porch 
of  the  building,  and  are  donned  just  before  stepping  over 
the  barrier,  so  that  they  never  come  into  contact  with  the 
ground  outside  the  clean  building.  The  barrier  is  usually 
a  strip  of  wood  about  eight  inches  high,  set  at  the  door  of 
the  building  to  denote  the  point  at  which  the  clean  area 
commences.  Magazines  and  some  other  buildings  can  be 
entered  by  wearing  leather  overshoes  kept  specially  for  the 
purpose,  but  this  is  not  permitted  in  all  buildings.  As  some 


INTRODUCTION  9 

explosives  are  easily  electrified,  it  is  advisable  that  workers' 
shoes  should  be  provided  with  a  few  copper  studs  in  the 
sole,  so  as  to  "  earth  "  the  wearer.  This  is  particularly 
the  case  when  reeling  cordite  and  when  handling  dry  gun- 
cotton.  Of  course  all  buildings  must  be  adequately  pro- 
tected against  lightning,  and  when  possible  work  must  be 
stopped  during  thunderstorms. 

The  manufacture  of  explosives  as  carried  out  in  this 
country  must  be  regarded  as  one  of  the  safest  of  the  dangerous 
trades,  the  average  number  of  fatalities  per  annum  for  the 
decade  1904-1914  being  7*7.  The  following  is  a  summary  of 
the  number  of  accidents,  deaths,  and  injuries  which  occurred 
in  manufacturing  operations  in  the  explosives  trade  during 
the  years  1911-1914  inclusive  : — 

Year. 
I9II 
1912 
1913 
1914  . . 

In  relation  to  the  number  of  accidents,  it  must  be  borne  in 
mind  that  any  accident  due  to  explosion,  no  matter  how 
trivial,  must  be  reported.  During  the  war  the  number  of 
accidents  and  the  number  of  killed  and  injured  greatly 
exceeded  these  figures,  but  this  must  be  ascribed  to  the 
enormously  increased  production,  accompanied  by  intensive 
working  and  dilution  of  labour. 

Imports  and  Consumption. — The  consumption  of  ex- 
plosives in  Great  Britain  is  chiefly  supplied  by  the  various 
explosive  factories  in  the  country,  but  some  explosive  is 
imported.  The  following  figures  denote  the  chief  blasting 
explosives  imported  in  1912  and  1913,  but  a  large  pro- 
portion was  only  imported  in  transit  and  was  not  con- 
sumed : — 

1912.  1913. 

Blasting  Gelatine          ..          ..     17,512  Ibs.  240,393153. 

Dynamite  ..          ..          ..   116,370  ,,  218,741  „ 

Gelignite  280,488  „  686,995  „ 


No.  of 

Accidents. 

Killed. 

Injured 

.    69 

13 

40 

.      104 

I 

33 

.       86 

13 

50 

.       92 

21 

4i 

10 


EXPLOSIVES 


No  data  is  available  as  regards  the  consumption  of 
sporting  powder,  but  the  consumption  of  blasting  explosives 
is  reported  under  the  Mines  and  Quarries  Act,  and  the  figures 
for  1910  and  1911  give  a  good  idea  of  the  extent  of  the 
industry — 


Gunpowder 

Permitted  Explosives 

Gelignite 

Gelatine  Dynamite 

Blasting  Gelatine 

Cheddite 

Other  Explosives 

Total 


1910. 

17,664,483  Ibs 
8,607,882 


494,560 
257.756 

123,584 
350,600 


..  30,538,121 


1911. 
17,305,073  Ibs 

9,340,033 

3,294,423 

472,464 

244,*55 
110,761 

530>979 
31,297,888 


In  the  United  States  the  industry  is  much  larger  than  in 
this  country,  the  home  consumption  for  the  years  1914-1917 
being — 

1914.     1915.     1916.      1917. 

Black  Blasting  Powder  206,099,700  197,722,300  215,575,025  277,118,525 
High  Explosives  ..  218,453,971  235,828,587  255,154,787  262,316,080 
Permissible  Explosives  25,697,818  27,349,909  34,685,240  43,040,722 


Total 


450,251,489  460,900,796  5°5,4I5,°52  582,475,327 


all  amounts  being  in  pounds.  L,arge  as  these  figures  are, 
they  do  not  include  the  very  considerable  export  trade 
carried  on,  the  figures  for  which  during  the  corresponding 
years  were — 


Year. 

Dynamite,  etc. 

Gunpowder. 

Cartridges. 

Other 
explosives. 

Weight 
(Ibs.) 

Value  (U.S. 
Dollars.) 

Weight 
(Ibs.) 

Value  (U.S. 
Dollars.) 

Value  (U.S. 
Dollars.) 

Value  (U.S. 
Dollars.) 

1914 

1915 
1916 
1917 

11,296,115 
11,446,368 
18,601,285 
17,930,665 

1,213,600 
1,509,050 
4.173,175 
3,653,374 

896,569 

84,358,379 
303,648,981 
446,540,999 

291,453 
66,922,807 
262,116,893 
331,163,229 

6,567,122 
25,408,079 
55,103,904 
42,122,656 

1,965,412 
95,129,957 
394,136,334 
255,944,315 

Classification. — The  following  is  the .  British  Official 
classification  of  explosives  extracted  verbatim  from  the 
"  List  of  Authorized  Explosives,"  1918  :— 


INTRODUCTION  n 

Class  I. — Gunpowder 

The  term  "  gunpowder  "  means  exclusively  gunpowder 
ordinarily  so  called. 

Class  II. — Nitrate  Mixture 

The  term  "  nitrate  mixture  "  means  any  preparation, 
other  than  gunpowder  ordinarily  so  called,  formed  by  the 
mechanical  mixture  of  a  nitrate  with  any  form  of  carbon 
or  with  any  carbonaceous  substance  not  possessed  of  ex- 
plosive properties,  whether  sulphur  be  or  be  not  added  to 
such  preparation,  and  whether  such  preparation  be  or  be  not 
mechanically  mixed  with  any  other  non-explosive  substance. 

Every  blasting  explosive  of  this  class,  in  which  nitrate  of 
ammonium,  nitrate  of  sodium  or  chloride  of  sodium  are  used 
as  ingredients,  shall  be  contained  in  cartridge  wrappers  or  cases 
(or  in  5  Ib.  inner  packages)  made  thoroughly  waterproof 
with  melted  paraffin  or  other  suitable  waterproofing  material. 

Class  III. — Nitro-Compound 

The  term  "  nitro-compound  "  means  any  chemical  com- 
pound possessed  of  explosive  properties,  or  capable  of  com- 
bining with  metals  to  form  an  explosive  compound,  which 
is  produced  by  the  chemical  action  of  nitric  acid  (whether 
mixed  or  not  with  sulphuric  acid)  or  of  a  nitrate  mixed 
with  sulphuric  acid  upon  any  carbonaceous  substance, 
whether  such  compound  is  mechanically  mixed  with  other 
substances  or  not. 

The  nitro-compound  class  has  two  divisions. 

Every  explosive  of  this  class  and  every  explosive  in- 
gredient thereof  shall  be  so  thoroughly  purified  and  other- 
wise of  such  a  character  as  to  satisfy  a  test  known  as  the 
Heat  Test,  and  specified  in  a  Memorandum  signed  by  a 
Government  Inspector  and  dated  the  2nd  of  February,  1914.* 

Every  blasting  explosive  in  this  class,  in  which  nitrate 
of  ammonium,  nitrate  of  sodium  or  chloride  of  sodium  are 

*  See  Section  IX. 


12  EXPLOSIVES 

used  as  ingredients,  shall  be  contained  in  cartridge  wrappers 
or  cases  (or  in  5  Ib.  inner  packages)  made  thoroughly  water- 
proof with  melted  paraffin  or  other  suitable  waterproofing 
material. 

Division  i  comprises  any  chemical  compound  or  mechanic- 
ally mixed  preparation  which  consists  either  wholly  or  partly 
of  nitroglycerine  or  of  some  other  liquid  nitro-compound. 

Provided  that  every  explosive  in  this  Division  shall  be 
of  such  a  character  and  consistency  as  not  to  be  liable  to 
liquefaction  or  exudation. 

Provided  also  that  an  explosive  that  is  required  by 
definition  to  be  issued  in  waterproof  inner  packages  may 
be  exempted  from  such  requirement  by  Special  Authority, 
when  and  so  long  as  the  conditions  of  such  Authority  are 
observed. 

Division  2  comprises  any  nitro-compound  as  before 
defined,  which  is  not  comprised  in  the  first  division. 

Class  IV. — Chlorate  Mixture 

The  term  "  chlorate  mixture "  means  any  explosive 
containing  a  chlorate. 

The  chlorate  mixture  class  has  two  divisions. 

Every  explosive  of  this  class,  and  every  explosive  in- 
gredient thereof,  shall  be  so  thoroughly  purified  and  other- 
wise of  such  a  character  as  to  satisfy  a  test  known  as  the 
Heat  Test,  and  specified  in  a  Memorandum  signed  by  a 
Government  Inspector  and  dated  the  2nd  February,  1914.* 

Bvery  blasting  explosive  in  this  class  in  which  nitrate 
of  ammonium,  nitrate  of  sodium  or  chloride  of  sodium  are 
used  shall  be  contained  in  cartridge  wrappers  or  cases  (or 
in  5  Ib.  inner  packages)  made  thoroughly  waterproof  with 
melted  paraffin  or  other  suitable  waterproofing  material. 

Division  i  comprises  any  chlorate  preparation  which 
consists  partly  of  nitroglycerine  or  of  some  other  liquid 
nitro-compound.  f 

Provided  that  every  explosive  in  this  Division  shall  be 

*  See  Section  IX. 

t  No  explosive  of  this  division  is  at  present  authorized. 


INTRODUCTION  13 

of  such  a  character  and  consistency  as  not  to  be  liable  to 
liquefaction  or  exudation. 

Division  2  comprises  any  chlorate  mixture  as  before 
defined,  which  is  not  comprised  in  the  first  division. 

Class  V. — Fulminate 

The  term  "fulminate"  means  any  chemical  compound 
or  mechanical  mixture,  whether  included  in  the  foregoing 
classes  or  not,  which,  from  its  great  susceptibility  to  detona- 
tion, is  suitable  for  employment  in  percussion  caps  or  any 
other  appliances  for  developing  detonation,  or  which,  from 
its  extreme  sensibility  to  explosion,  and  from  its  great 
instability  (that  is  to  say,  readiness  to  undergo  decomposition 
from  very  slight  exciting  causes),  is  especially  dangerous. 

This  class  consists  of  two  divisions. 

Division  i  comprises  such  compounds  as  the  fulminates 
of  silver  and  of  mercury,  and  preparations  of  these  sub- 
stances, such  as  are  used  in  percussion  caps ;  and  any 
preparation  consisting  of  a  mixture  of  a  chlorate  with  phos- 
phorus, or  certain  descriptions  of  phosphorus  compounds, 
with  or  without  the  addition  of  carbonaceous  matter,  and 
any  preparation  consisting  of  a  mixture  of  a  chlorate  with 
sulphur,  or  with  a  sulphuret,  with  or  without  carbonaceous 
matter.* 

Division  2  comprises  any  such  substance  as  the  chloride 
and  the  iodide  of  nitrogen,  fulminating  gold  and  silver, 
diazobenzol,  and  the  nitrate  of  diazobenzol.f 

Class  VI. — Ammunition 

The  term  "  ammunition  "  means  an  explosive  of  any  of 
the  foregoing  classes  when  enclosed  in  any  case  or  con- 
trivance, or  otherwise,  adapted  or  prepared  to  form  a 
cartridge  or  charge  for  small  arms,  cannon,  or  any  other 
weapon,  or  for  blasting,  or  to  form  any  safety  or  other  fuze 
for  blasting,  or  for  shells,  or  to  form  any  tube  for  firing 

*  The  only  explosive  of  this  division  at  present  authorized  is  mercury 
fulminate. 

f  The  only  explosive  of  this  division  at  present  authorized  is  lead  azide. 


14  EXPLOSIVES 

explosives,  or  to  form  a  percussion  cap,  a  detonator,  a  fog- 
signal,  a  shell,  a  torpedo,  a  war  rocket,  or  other  con- 
trivance other  than  a  firework. 

The  term  "  percussion  cap  "  does  not  include  a  deto- 
nator.* 

The  term  "  detonator  "  means  a  capsule  or  case  which 
is  of  such  strength  and  construction  and  contains  an  ex- 
plosive of  the  fulminate  explosive  class  in  such  quantity 
that  the  explosion  of  one  capsule  or  case  will  communicate 
the  explosion  to  other  like  capsules  or  cases. 

The  term  "  safety  fuze  "  means  a  fuze  which  burns  and 
does  not  explode,  and  which  does  not  contain  its  own  means 
of  ignition,  and  which  is  of  such  strength  and  construction 
and  contains  an  explosive  in  such  quantity  that  the  burning 
of  such  fuze  will  not  communicate  laterally  with  other 
like  fuzes. 

The  ammunition  class  has  three  divisions. 

Division  i. — No  official  definition  of  Division  i  is  given, 
but  it  includes  safety  electric  fuzes,  percussion  caps  and 
railway  fog-signals. 

Division  2  comprises  any  ammunition  as  before  defined 
which  does  not  contain  its  own  means  of  ignition,  and  is  not 
included  in  Division  i. 

Division  3  comprises  any  ammunition  as  before  defined 
which  contains  its  own  means  of  ignition  and  is  not  included 
in  Division  i. 

Class  VII. — Firework 

The  term  "  firework  "  comprises  firework  composition 
and  manufactured  fireworks. 

Division  i. — Firework  composition.! 

Division  2. — Manufactured  fireworks,  consisting  of  any 

*  A  percussion  cap  can  only  be  properly  classed  as  such  if  it  contains 
less  than  *6  grain  of  a  composition  of  the  ist  Division  of  the  5th  (Fulminate) 
class  of  which  not  more  than  25  per  cent,  consists  of  fulminate  of  mercury, 
or  less  than  '5  grain  of  any  other  explosive  of  the  ist  Division  of  the  5th 
(Fulminate)  class.  And  it  has  been  further  decided  that  percussion  caps 
shall  not  be  classed  as  such  when  they  contain  anvils  or  have  their  composi- 
tion unprotected  by  tinfoil  or  other  suitable  substance. 

f  No  explosive  of  this  division  is  at  present  authorized. 


INTRODUCTION  15 

explosive  of  the  foregoing  classes,  and  any  firework  com- 
position, when  such  explosive  or  composition  is  enclosed  in 
any  case  or  contrivance,  or  is  otherwise  manufactured  so 
as  to  form  a  squib,  cracker,  serpent,  rocket  (other  than  a  war 
rocket),  maroon,  lance,  wheel,  and  Chinese  fire,  Roman 
candle,  or  other  article  specially  adapted  for  the  production 
of  pyrotechnic  effects  or  pyrotechinc  signals,  or  sound 
signals.  Provided  that  a  substantially  constructed  and 
hermetically  closed  metal  case  containing  not  more  than 
i  Ib.  of  coloured  fire  composition  of  such  a  nature  as  not  to 
be  liable  to  spontaneous  ignition  shall  be  deemed  to  be 
a  manufactured  firework.  Provided  also  that  the  term 
"  manufactured  firework  "  shall  not  be  deemed  to  include 
any  explosive  hereinafter  mentioned,  by  whatever  name 
known,  or  any  colourable  imitation  of  the  same. 


BIBLIOGRAPHY 

A.  Marshall,  "  Explosives."    London,  1917. 
O.  Guttmann,  "  Manufacture  of  Explosives."    London,  1895. 
P.  C.  Sanford,  "  Nitroexplosives."    London,  1906. 
E.  de  W.  S.  Colver,  "  High  Explosives."    London,  1918. 
W.  Walke,  "  Lectures  on  Explosives."    London,  1897. 
H.  W.  L.  Hime,  "  Gunpowder  and  Ammunition."    London,  1904. 
E.  M,  Weaver,  "  Military  Explosives."     London,  1917. 
R.  Molina,  "  Les  Explosifs  et  leur  Fabrication."    French  translation  by 
J.  A.  Montpelier.     Paris,  1909. 

J.  Daniel,  "  Dictionaire  des  Matieres  Explosives."    Paris,  1902. 
L.  Gody,  "  Matieres  Explosives."    Paris,  1907. 
L.  Vennin  and  G.  Chesneau,  "  Poudres  et  Explosifs."     Paris,  1914. 
P.  F.  Chalon,  "  Les  Explosifs  Modernes."    Paris,  1911. 
R.  Escales,  "  Die  Explosivstoffe."    Leipzig,  1905-1915. 
Heft  I.  "  Schwartzpulver  u.  Sprengsalpeter."     1914. 
Heft  II.,  "  Schiessbaumwolle."     1905. 
Heft  III.,  "  Nitroglyzerin  u.  Dynamit."     1908. 
Heft  IV.,  "  Ammonsalpetersprengstoffe."     1909. 
Heft  V.,  "  Chloratsprengstoffe."     1910. 
Heft  VI.,  "  Nitrosprengstoffe."     1915. 

H.  Brunswig,  "  Die  Explosivstoffe."    English  translation  by  C.   E. 
Munroe  and  A.  L.  Kibler.     New  York,  1912. 

A.  Voigt,  "  Die  Hertsellung  der  Sprengstoffe."    Halle,  1913-1914. 
Theil  I.    Schwartzpulver. 

Chloratsprengstoffe. 
Schiessbaumwolle . 
Rauchschwache  Schiesspulver. 
Theil  II.  Nitroglyzerin. 
Dynamit. 
Sicherheitssprengstoffe. 


16  EXPLOSIVES 

F.  Salvati,  "  Volcabolario  di  Polveri  Ed  Explosivi."     Rome,  1893. 

R.  Aranaz,  "  Los  Explosives  Militates."     Granada,  1904. 

J.  M.  Vivas»  J.  R.  Feigenspan,  and  J.  F.  Ladreda,  "  Polvoras  y  Explo- 
sives." Segovia,  1915. 

An  invaluable  book  on  the  legislation  affecting  the  manufacture  and 
storage  of  explosives  has  been  prepared  by  Capt.  J.  H.  Thomson,  entitled 
"  Guide  to  the  Explosives  Act,  1875."  The  last  edition  was  published  in 
1917. 

A  bibliography  of  the  chief  works  on  ballistics  will  be  found  at  the  end 
of  the  section  on  Propellants. 

The  chief  periodicals  dealing  with  explosives  are — 

Arms  and  Explosives .    London . 

Zeitschrift  f.  Gesamte  Schiess-  und  Sprengstoff-wsen.     Munich. 

Sprengstoffe,  Waffen  u.  Munition.     Berlin. 

Memorial  des  Poudres  et  Salpetres.     Paris. 

Very  valuable  information  is  also  published  from  time  to  time  in  the 
"  Bulletins  "  and  "  Technical  Papers  "  of  U.S.  Bureau  of  Mines  and  the 
U.S.  Bureau  of  Explosives. 


SECTION  L— GUNPOWDER 

GUNPOWDER  remained  the  only  known  explosive  until  the 
middle  of  the  nineteenth  century,  and  at  the  present  time 
is  still  the  most  used  explosive  except  for  military  purposes. 
For  military  purposes  its  use  is  now  limited  to  bursting 
charges  for  shrapnel  shell,  to  time  fuzes,  and  to  priming 
composition  for  use  with  cordite,  but  it  is  still  largely  used 
as  a  sporting  powder,  chiefly  on  account  of  its  cheapness. 
The  same  consideration,  and  the  fact  that  it  does  not  require 
a  detonator,  has  led  to  its  retention  for  blasting  purposes, 
about  55  per  cent,  of  the  explosive  used  for  blasting  in 
Great  Britain  in  1911  being  gunpowder. 

Compared  with  modern  high  explosives  Gunpowder  is 
greatly  lacking  in  power,  the  Trauzl  block  test  giving  figures 
of  about  108  as  compared  with  520  for  Dynamite  No.  i 
and  650  for  Blasting  Gelatine.  Gunpowder  has  the  advantage, 
however,  of  being  less  brisant  than  most  explosives,  a  great 
advantage  when  dealing  with  soft  material  which  it  is 
desired  to  obtain  in  big  lumps. 

Gunpowder  invariably  consists  in  this  country  of  a 
mixture  of  potassium  nitrate,  sulphur,  and  charcoal,  although 
in  America  and  in  Germany  large  quantities  are  consumed  in 
which  the  cheaper  sodium  nitrate  has  been  substituted  for 
the  potassium  salt.  These  sodium  nitrate  powders  are 
cheaper  and  somewhat  more  powerful  than  those  made 
with  potassium  nitrate,  but  their  deliquescent  properties 
are  a  great  drawback.  They  have  been  used  in  Great 
Britain  since  the  outbreak  of  war  cut  off  the  potash 
supplies  from  Germany. 

In  manufacturing  gunpowder  some  care  is  required  in 
the  selection  of  material.  The  nitre  should  be  almost 
chemically  pure,  be  quite  neutral  to  litmus,  and  quite  free 
T.  2 


i8  EXPLOSIVES 

from  chlorate  and  perchlorate,  especially  the  former.  It 
should  not  contain  more  than  the  merest  trace  of  chloride, 
under  -01  per  cent,  calculated  as  NaCl,  as  otherwise  it  will 
become  deliquescent. 

The  sulphur  must  contain  no  non-volatile  matter,  and 
must  be  free  from  sulphuric  acid.  As  commercial  flowers 
of  sulphur  almost  invariably  contains  some  acid,  it  is  usual 
to  use  roll  sulphur  and  grind  this  down.  The  quality  of  the 
powder  depends  a  great  deal  on  the  quality  of  the  charcoal, 
so  that  it  is  customary  for  powder  mills  to  prepare  their  own. 
The  wood  most  employed  in  this  country  is  alder  wood  and 
dog  wood,  but  hazel,  willow,  yew,  hemp,  and  poplar  are  all 
used.  The  German  cocoa  powder,  one  of  the  best  gunpowder 
propellants  for  cannon  ever  made,  was  prepared  from 
rye  straw  charcoal.  It  has,  however,  been  completely 
superseded  by  the  modern  smokeless  powders. 

Timber  intended  for  gunpowder  charcoal  should  be 
cut  in  the  spring,  and  then  kept  for  from  three  months  to 
three  years  in  order  to  allow  the  sap  to  evaporate.  The 
bark  is  then  removed  and  the  wood  cut  up  and  carbonized 
in  iron  cylinders. 

Various  forms  of  retorts  have  been  proposed,  but  the 
most  generally  used  is  in  the  form  of  a  cylinder  4  ft.  6  in.  long 
by  2  ft.  4  in.  diameter.  These  are  charged  with  the  wood 
and  then  closed,  except  for  a  vent  to  allow  the  escape  of  the 
products  of  distillation.  The  retort  is  then  slid  into  the 
furnace  and  carbonization  carried  out  for  4  to  5  hours  at 
a  temperature  between  400°  C.  and  500°  C.  The  crude 
pyroligneous  acid  that  distils  off  can  be  collected  and  worked 
up  for  acetic  acid,  acetone,  etc.,  but  the  amounts  are  so 
small  that  the  distillate  is  usually  led  direct  to  the  furnace 
and  burnt.  When  carbonization  is  complete  the  retort  is 
removed  from  the  furnace,  completely  closed  and  set  aside 
to  cool.  Air  must  not  be  admitted  until  the  charge  has 
cooled,  and  even  then  only  slowly,  as  freshly  made  charcoal 
absorbs  air  with  avidity,  and  may  inflame.  It  is  for  this 
reason  that  movable  retorts  are  usually  preferred  to  fixed 
ones,  although  both  types  are  used. 


GUNPOWDER  ig 

The  composition  of  gunpowder  varies  a  good  deal  with 
the  different  grades  manufactured.  French  military  powders 
remained  of  the  same  composition  from  1598  until  the 
adoption  of  the  modern  smokeless  powders.  They  were 
made  according  to  the  famous  recipe  "  As,  as,  six,"  viz. 
i  part  of  sulphur,  i  part  of  charcoal,  and  6  parts  of  nitre. 
This  corresponds  to  nitre  75  per  cent.,  and  sulphur  and 
charcoal  12*5  per  cent.  each.  The  following  table  gives  the 
composition  of  a  few  modern  powders  made  by  different 
countries,  but  it  must  be  borne  in  mind  that  various  grades 
of  powder  are  in  use  : — 

Sporting  powder.  Blasting  powder. 

Country.                                KNO3  S  C  KNO3             S  C 

Great  Britain    .          .          . .   75  10  15  65-75  10-20  15 

(Ordinaire       .          ..  —  —  —  62             20  18 

France]  Lente             .          ..78  10  12  40             30  30 

(Forte              ...  —  72             13  15 

..78  10  12  65-70  14-20  16 

..   76           9*4  14*6  60-2  184  2i'4 


Germany 
Austria 


In  the  manufacture  of  gunpowder  the  ingredients  are 
first  ground  separately  in  any  suitable  form  of  mill.  Char- 
coal should  not  be  ground  for  at  least  a  fortnight  after 
burning,  as  otherwise  it  may  inflame  through  the  absorption 
of  oxygen.  Sulphur  in  grinding  requires  care,  as  it  is  easily 
electrified,  and  consequently  sulphur  mills  should  be  care- 
fully earthed.  Precautions  should  also  be  taken  against 
a  dust  explosion,  and  the  same  applies  to  charcoal. 

The  actual  manufacture  of  gunpowder  in  a  modern 
factory  involves  seven  operations,  or  eight  in  the  case  of 
moulded  powders.  The  object  in  the  rather  elaborate 
procedure  is  to  obtain  a  uniform  powder,  which  will  not 
separate  and  the  grains  of  which  will  not  crumble. 

First  Mixing. — This  is  carried  out  either  in  a  copper 
ball  mill  with  lignum  vitae  balls,  or  in  a  revolving  drum 
through  which  passes  a  shaft  carrying  eight  arms  or  "  flyers." 
The  drum  and  shaft  revolve  in  opposite  directions,  the  former 
making  60  revolutions  per  minute  and  the  latter  120. 
A  uniform  mixture  is  obtained  in  a  few  minutes,  and  the 
"  green  "  charge  then  emptied  out,  sifted,  and  removed  to 
the  incorporating  house. 


20 


EXPLOSIVES 


FIG.  i. — Gunpowder  Incorporating 
Machine 


Incorporating  or  Milling. — This  was  formerly  carried 
out  in  stamp  mills,  and  these  are  still  in  use  in  some  of  the 
smaller  continental  works,  but  are  being  rapidly  replaced 

by  edge  runners.  These 
consist  of  stone  runners 
acting  on  a  stone  bed,  or 
of  iron  runners  on  an  iron 
or  hard  wood  bed.  Stone 
must  not  run  on  iron,  or 
vice  versa,  on  account  of 
the  danger  of  sparks.  The 
runners  weigh  4  to  5  tons 
each,  and  are  set  at  dif- 
ferent distances  from  the 
driving  shaft,  so  that  they 
do  not  run  on  the  same 
path.  Each  is  provided 

with  a  scraper  to  prevent  its  picking  up  cake,  and  with  a 
phosphor  bronze  or  hard  wood  plough  to  push  the  charge 
into  its  path.  In  the  best  type  of  incorporating  mill  the 
runners  do  not  rest  on  the 
bed,  but  are  suspended  a 
short  distance  above  it, 
and  each  is  capable  of 
an  independent  vertical 
movement,  so  as  to  allow 
it  to  pass  over  any  extra 
hard  lumps  without  un- 
due friction  (Figs,  i  and 
2).  In  Germany  this 
arrangement  is  compul- 
sory if  iron  runners  and 
an  iron  bed  are  used.  A 

.,  f  , .  FIG.  2. — Gunpowder  Incorporating 

charge  for  incorporation  Machine. 

is  50-80  Ibs.  and  requires 

from  3-8  hours,  depending  on  the  nature,  of  the  powder. 
Moisture,  in  the  form  of  condensed  steam  from  the  drying 
stoves,  is  added  from  time  to  time  so  as  to  maintain  a 


GUNPOWDER  21 

water  content  of  3-6  per  cent.  After  incorporation  is 
complete,  the  charge  is  removed  and  roughly  broken  up 
by  hand,  and  is  then  ready  for  pressing.  Any  hard  in- 
crustation that  remains  in  the  incorporating  mill  must 
be  thoroughly  soaked  in  water,  and  then  removed  with 
a  wooden  tool.  Incorporation  is  a  somewhat  dangerous 
process,  and  in  this  country  special  safety  arrangements 
must  be  provided.  These  consist  of  a  water  tank  over  each 
machine  connected  with  a  large  board  directly  above  the 
incorp orator,  so  that  any  movement  of  the  board  caused 
by  an  explosion  wave  tips  the  whole  contents  of  the  tank 
on  to  the  charge  and  drowns  it.  All  the  tanks  in  each 
house  are  interconnected,  so  that  the  movement  of  any 
board  actuates  them  all.  Usually  six  machines  are  placed 
in  each  house,  each  machine  being  separated  by  a  strong 
partition  of  masonry.  Should  the  charge  in  any  one  mill 
explode,  the  force  of  the  explosion  wave  acting  on  the  board 
above  it  tips  all  the  tanks  in  the  building,  and  so  prevents 
the  explosion  spreading. 

Pressing. — This  is  carried  out  in  hydraulic  presses 
capable  of  dealing  with  about  1000  Ibs.  at  a  time.  The 
presses  are  charged  as  follows.  A  copper  or  ebonite  plate 
is  laid  in  a  horizontal  position  and  surrounded  by  a  light 
wooden  frame  about  i  in.  deeper  than  the  thickness  of  the 
plate.  The  tray  thus  formed  is  filled  with  the  powder  to 
be  pressed,  and  this  carefully  smoothed  off  level  with  the  top 
of  the  wooden  frame.  Another  plate  is  then  placed  on  the 
top  of  this,  and  this  surrounded  by  another  wooden  frame, 
and  the  tray  thus  formed  filled  with  powder.  This  is 
repeated  until  the  full  number  of  plates  have  been  used, 
usually  20-30.  The  size  of  the  plates  varies  in  different 
factories,  but  they  are  usually  about  2  ft.  4  in.  by  i  ft.  8  in. 
The  wooden  frames  are  then  removed  and  the  pile  slid  into 
an  hydraulic  press  with  upward  moving  ram  (Fig.  3).  The 
pressure  applied  is  about  400  Ibs.  per  square  inch,  but  it  is 
best  measured  by  watching  the  movement  of  the  ram  and 
not  by  gauges.  It  must  be  applied  slowly,  the  time  occupied 
being  about  2  hours.  When  pressing  is  complete  the  plates 


22 


EXPLOSIVES 


14 


are  picked  off  one  by  one,  and  the  outer  edge  of  each  cake 

to  a  depth  of  about  ij 
in.  cut  off  and  kept  sepa- 
rate from  the  main  bulk. 
This  is  done  as  the  peri- 
phery has  not  sustained 
the  full  pressure.  The 
cuttings  are  given  a 
short  milling  and  then 
repressed,  whereas  the 
main  bulk  passes  on  to 
the  granulating  machine. 
Pressing  is  a  some- 
what dangerous  process, 
and  an  explosion  is 
usually  very  disastrous 
on  account  of  the  large 
quantity  of  powder  be- 
ing dealt  with.  In  order 
to  protect  the  workers 
all  controls  should  be  in 
a  special  room  sepa- 
rated from  the  press  by 
a  strong  wall,  arrange- 
ments being  made  for 
the  workman  to  observe 
the  movement  of  the 
ram  without  entering 
the  press  room. 

In  this  country  plates 
of  ebonite  are  preferred 
to  those  of  copper,  as 
they  are  not  so  easily 
deformed  and  transmit 
thepressure  more  evenly. 
On  the  other  hand  they 
are  easily  electrified, 
FIG.  3.— Gunpowder  Press.  and  Guttmann  records 


GUNPOWDER  23 

one  fatal  explosion  in  which  the  workman  observed  a  spark 
4  in.  long  pass  from  his  hand  to  the  press.  Needless  to 
say,  presses  should  be  carefully  earthed. 

Granulating  or  Corning.— In  this  process  the  press 


FIG.  4. — Arrangement  of  Granulating  Machine. 


24  EXPLOSIVES 

cakes  are  broken  up  into  grains  of  the  desired  size  by  passing 
them  through  a  series  of  three  or  more  pairs  of  toothed  gun- 
metal  rollers  revolving  towards  one  another.  Between 
each  pair  of -rollers  are  vibrating  screens  of  gun-metal  wire 
which  separate  the  powder  into  three  sizes,  viz.  oversize, 
which  passes  on  to  the  next  set  of  rollers  ;  right  size,  which 
is  collected  for  the  next  stage ;  and  undersize,  which  is 
collected  and  remilled  and  pressed.  The  construction  of 
a  granulating  machine  is  shown  diagrammatically  in  Fig.  4. 
The  rollers  should  be  mounted  with  spring  bearings,  so  that 
if  they  encounter  an  extra  hard  piece  of  cake  they  can  open 
and  let  it  pass  (Fig.  5).  Powders  made  from  dogwood 


FIG.  5. — Rollers  of  Granulating  Machine.     Detail  showing  Spring 
Bearings. 


charcoal  usually  produce  a  great  deal  of  dust,  and  are 
generally  given  an  extra  screening  ("  dusting  ")  to  remove 
this. 

Glazing. — This  is  carried  out  in  revolving  wooden 
drums,  and  has  the  effect  of  rounding  off  the  grains  and 
improving  their  appearance.  A  little  graphite  is  sometimes 
added  when  slow-burning  powders  are  being  made. 

Stoving  or  Drying. — This  is  carried  out  by  spreading 
the  powder  in  thin  layers  on  trays,  consisting  of  a  wooden 
frame  with  a  canvas  bottom.  Drying  is  carried  out  at 
40°  C.  by  blowing  air  heated  by  means  of  hot  water  pipes 
into  the  building. 

Blending. — This  consists  in  mixing  several  batches  so  as 
to  obtain  a  uniform  product. 


GUNPOWDER  25 

Moulding. — Before  smokeless  powders  were  introduced 
suitable  slow-burning  powders  for  use  with  rifled  ordnance 
were  prepared  by  compressing  the  blended  gunpowder 
into  cubes,  pyramids,  or  prisms  with  from  one  to  eight 
perforations.  The  German  cocoa  powder  was  especially 
suited  for  making  moulded  powders,  as  it  flowed  well  in  the 
die.  The  perforations  had  the  object  of  obtaining  a  more 
constant  rate  of  combustion.  These  moulded  powders  are 
no  longer  manufactured,  but  moulded  cartridges  are  used 
for  blasting  purposes.  These  are  simply  prepared  by 
measuring  a  definite  amount  of  powder  into  a  die  and  then 
compressing  it  by  means  of  two  pistons,  one  working  up- 
wards and  one  downwards,  actuated  by  mechanical  or 
hydraulic  means.  The  lower  piston  carries  a  plunger  which 
enters  a  prepared  hole  in  the  upper  piston,  and  so  leaves  a 
perforation  in  the  cartridge  in  which  the  fuze  can  be  inserted. 

Sodium  Nitrate  Powders. — Powders  in  which  the 
potassium  nitrate  has  been  replaced  by  the  cheaper  sodium 
salt  are  used  in  gigantic  quantities  in  America.  They  are 
somewhat  more  powerful  than  ordinary  gunpowder,  but  their 
chief  attraction  lies  in  their  cheapness.  They  suffer  from 
the  great  disadvantage,  however,  of  being  very  hygroscopic. 
They  are  made  in  much  the  same  way  as  ordinary  powder, 
and  have  an  average  composition — 

Sodium  nitrate  . .          . .  74 

Sulphur  . .         . .         . .  10 

Carbon  . .         . .         . .  16 

Although  the  annual  consumption  of  this  type  of  powder 
in  the  United  States  amounts  to  nearly  a  hundred  million 
pounds  (50,000  short  tons),  it  was  not  used  in  Great  Britain 
until  the  outbreak  of  war  in  1914  cut  off  the  supply  of  potash 
and  compelled  the  Government  to  alter  the  definition  of 
gunpowder,  so  as  to  include  powders  made  with  sodium 
nitrate.  A  very  similar  powder  is  much  used  in  Germany 
under  the  name  "  Sprengsalpeter."  It  is  composed  of — 

Sodium  nitrate  . .  •  •  75 
Brown  coal  (lignite)  . .  . .  15 
Sulphur  10 


26 


EXPLOSIVES 


It  is  regarded  as  safer  than  ordinary  powder,  and  in 
Germany  can  be  sent  in  unrestricted  amount  by  goods  train. 

"  Bobbinite  "  is  a  form  of  gunpowder,  and  is  the  favourite 
coal-getter  in  this  country.  It  does  not  pass  the  Rotherham 
test,  but  its  use  under  certain  restrictions  was  specially 
permitted  for  a  term  of  five  years  from  January  ist,  1914,  and 
by  a  further  Order  in  Council  dated  September  i8th,  1918, 
this  period  has  been  extended  until  December  3ist,  1920. 
It  is  defined  in  the  Explosives  in  Coal  Mines  Order  of  Sep- 
tember ist,  1913,  as  having  the  composition — 


Ingredients. 

ist  definition. 

2nd 

definition. 

Potassium  Nitrate 
Charcoal 
Sulphur 

Maximum,    i 
65 
i9'5 
2'5 

Minimum. 
62 

I? 

Maximum 
66 
20*5 
2'5 

.    |     Minimum. 
63 
18-5 

i'5 

Ammonium  Sulphate 
Copper  Sulphate  . . 
Rice  or  Maize  Starch 
Paraffin  Wax 
Moisture    , 


I7 


13 


7 
2'5 


It  is  manufactured  in  moulded  pellets,  each  pellet  being 
coated  with  paraffin  wax  and  wrapped  in  brown  paper. 
Bobbinite  made  according  to  the  first  definition  must  have 
a  density  not  exceeding  1*42,  and  according  to  the  second 
definition  not  exceeding  1*48.  There  is  no  charge  limit, 
and  it  must  not  be  fired  with  a  detonator. 

Stability,  etc. — Gunpowder  is  to  be  regarded  as  a  very 
safe  explosive.  It  ignites  when  heated  at  270°-300°  C.,  and 
is  fired  when  struck  by  a  two-kilogram  weight  falling  a 
distance  of  70-100  cm.,  the  powder  being  confined  between 
hardened  steel  surfaces.  It  is  completely  ruined  by  water, 
and  powder  that  has  been  damp  does  not  regain  its  full 
strength  on  drying.  This  is  due  to  the  moisture  dissolving 
part  of  the  nitrate  which  crystallizes  out  on  drying,  and 
spoils  the  intimate  mixing  of  the  ingredients  so  necessary 
in  order  to  obtain  a  good  explosive.  On  explosion,  it  gives 
about  44  per  cent,  of  gaseous  and  56  per  cent,  of  solid 
products.  The  gaseous  products  of  explosion  are  chiefly 


GUNPOWDER  27 

nitrogen,  carbon  dioxide  and  carbon  monoxide,  together  with 
small  quantities  of  hydrogen,  methane,  and  sulphuretted 
hydrogen.  The  solid  products  are  chiefly  composed  of 
carbonate  and  sulphate  of  potassium,  together  with  some 
unburnt  sulphur  and  traces  of  sulphide,  thiocyanate,  and 
nitrate  of  potassium. 

One  gram  of  powder  yields  from  250  to  300  cc.  of  perma- 
nent gas  measured  at  N.T.P.,  and  evolves  from  500  to  700 
calories.  The  temperature  of  explosion  is  probably  about 
2700°  C. 


LITERATURE 

The  best  account  of  the  history  of  gunpowder  is  given  by  Col.  Hime  in 
"  Gunpowder  and  Ammunition."  London,  1904. 

A  full  description  of  the  manufacture  of  charcoal  and  sulphur  will  be 
found  in  R.  Escales,  "  Schwartzpulver  u.  Sprengsalpeter,"  Leipzig,  1914 ; 
and  in  O.  Guttmann,  "  Manufacture  of  Explosives,"  London,  1895. 

Information  on  the  products  of  explosion  will  be  found  in  the  following 
papers : — 

A.,  102,  325  ;  109,  53  ;  265,  257. 

Trans.  Roy.  Soc.,  1875,  49. 

Numerous  accidents  have  happened  during  the  manufacture  of  gun- 
powder, but  the  following  Special  Reports  are  selected  as  being  particularly 
instructive:  S.R.,  160,  165,  177,  179,  181,  189,  190,  202. 


SECTION  II.— EXPLOSIVE   COMPOUNDS 

THE  number  of  explosive  compounds  suitable  for  industrial 
use  is  very  limited,  owing  to  the  difficulty  in  combining 
suitable  physical  properties  with  sufficient  stability  and 
cheapness  of  manufacture.  Up  to  the  present,  with  the 
exception  of  fulminate  of  mercury  and  azide  of  lead,  both 
of  which  are  largely  used  for  detonators  and  percussion  caps, 
the  only  explosive  compounds  that  have  been  found  to 
fulfil  industrial  requirements  are  esters  of  nitric  acid  and 
aromatic  nitro-compounds.  Of  the  former  the  esters  of 
the  lower  alcohols  are  too  volatile  for  use,  while  those  of 
the  higher  alcohols  are  too  expensive  and  are  deficient  in 
oxygen.  Of  the  polyhydric  alcohols  glycerine  trinitrate 
is  far  the  most  used,  as  glycerine  can  be  obtained  at  a 
moderate  price  and  its  trinitrate  is  easily  prepared  and  is 
insoluble  in  water,  so  that  it  can  be  readily  washed  free 
from  acid.  For  special  purposes  the  tetranitrate  of  di- 
glycerine  and  the  dinitrate  of  monochlorhydrin  are  used. 
In  France  the  use  of  glycol  dinitrate  has  been  proposed, 
as  it  has  been  stated  that  glycol  can  be  obtained  from  acety- 
lene at  a  price  which  enables  it  to  compete  with  glycerine. 
Tartaric  acid  forms  a  dinitrate,  but  unfortunately  it  is 
too  unstable  for  use  as  an  explosive. 

The  other  polyhydric  alcohols  are  too  expensive  to 
allow  of  their  nitrates  finding  industrial  application,  although 
the  use  of  mannitol  hexanitrate  has  been  proposed.  If  these 
polyhydric  alcohols  could  be  obtained  at  a  reasonable  price 
their  nitrates  would  form  valuable  explosives,  as  the  per- 
centage of  available  oxygen  increases  with  the  number  of 
carbon  atoms  carrying  a  hydroxyl  group.  Thus,  glycol 
dinitrate  contains  no  available  oxygen — 


EXPLOSIVE   COMPOUNDS  29 

CH2ONO2 

|  =     CO2-fN2+2H2O 

CH2ON02 

whereas  glycerine  trinitrate  contains  3*5  per  cent,  and 
mannitol  hexanitrate  contains  7-1  per  cent. — 

2CH2ON02.CHON02.CH2ON02  =6C 
CH2ON02.  (CHON02)  4.CH2ONO2 =6CO2 

The  sugars  form  nitric  esters,  and  attempts  have  been 
made  to  use  glucose  nitrate  and  sucrose  nitrate.  Un- 
fortunately, the  nitric  esters  of  the  sugars  are  soluble  in 
water  and  are  hygroscopic  and  very  sensitive.  Polyhydric 
cyclohexanols  such  as  inosite  form  nitric  esters,  inosite 
forming  a  hexanitrate,  but  unfortunately  inosite  and  its 
derivatives  are  merely  chemical  curiosities  at  present. 

Of  the  fatty  hydroxyl  compounds  of  unknown  molecular 
weight  cellulose  and  starch  are  the  best  known,  and  both 
form  nitric  esters.  Of  these  the  cellulose  nitrates  are  very 
widely  used  (guncotton,  pyroxylin,  collodion  cotton),  and 
are  usually  made  from  cotton,  although  wood  cellulose  is 
used  to  some  extent.  There  are  mechanical  difficulties  in 
nitrating  starch  and  stabilizing  the  product  which  have 
prevented  the  use  of  starch  nitrates  up  to  the  present  time. 

Of  the  nitro-compounds  those  of  the  aliphatic  series 
would  be  useful  if  they  could  be  obtained  more  readily, 
tetranitromethane,  for  example,  containing  nearly  24  per 
cent,  of  available  oxygen — 

C(N02)4     =    C02+2N2+302 

Unfortunately  they  are  all  troublesome  and  expensive  to 
make,  and  those  having  hydrogen  atoms  attached  to  the 
same  carbon  atom  as  the  nitro-group  have  the  objectionable 
property  of  forming  unstable  salts  with  metals — 

H\          /O 
CH3N02    ->        >C=N<; 

W  XOM 

A  large  number  of  aliphatic  nitro-compounds  also  have 
objectionable  toxic  properties,  especially  tetranitromethane. 
Of  the  aromatic  hydrocarbons  benzene  forms  a  dinitro- 


30  EXPLOSIVES 

compound  easily,  and  a  trinitro-compound  with  such  great 
difficulty  that  it  is  little  more  than  a  chemical  curiosity. 
Toluol,  on  the  other  hand,  forms  a  trinitro-compound  with 
ease,  and  the  same  is  the  case  with  xylol.  Toluol  is  also 
fairly  easily  nitrated  in  the  side  chain  (B.P.  6o76n),  and 
readily  yields  nitrophenyl  nitromethane.  The  tetranitro- 
compound,  trinitrophenyl  nitromethane,  does  not,  however, 
seem  to  have  been  studied.  Of  the  other  aromatic  hydro- 
carbons naphthalene  gives  a  tetranitro-compound,  but  only 
with  some  difficulty,  so  that  the  mono-,  di-  and  tri-nitro- 
compounds  only  are  used. 

The  entrance  of  nitro-groups  into  the  nucleus  is  facilitated 
by  the  presence  of  amino  and  hydroxyl  groups.  Thus, 
aniline  gives  a  tetranitro-compound  with  some  difficulty, 
and  methyl  aniline  gives  a  tetranitro-compound  (trinitro- 
phenylmethyl  nitramine),  which  although  somewhat  ex- 
pensive for  ordinary  purposes,  are  used  for  detonators. 
Diphenylamine  gives  a  hexanitro- compound  which  has  found 
some  application,  but  unfortunately  the  nitro-groups  confer 
strongly  acidic  properties  on  the  imino  hydrogen  atom. 

Phenol  forms  a  trinitro-compound  (picric  acid),  and  so 
does  cresol.  Both  have  been  used,  but  both  are,  unfortu- 
nately, strongly  acidic. 

No  attempts  seem  to  have  been  made  to  utilize  com- 
pounds such  as  nitrobenzyl  nitrate,  although  these  should 
be  readily  obtained  by  nitrating  benzyl  alcohol.  Nitric 
esters  are  always  less  stable  than  nitro- compounds,  so  that 
substances  containing  both  groups  might  be  useful  for 
detonators  if  for  no  other  purpose. 

The  aromatic  diazo  salts  are  all  explosive,  but  as  a  rule 
are  too  sensitive  and  too  deficient  in  oxygen  to  be  of  any 
practical  value.  Attempts  have  been  made,  however,  to 
use  ^>-nitrodiazobenzene  nitrate  for  detonators,  but  without 
much  success. 

It  should  be  noted  that  all  aromatic  nitro-compounds 
are  very  deficient  in  oxygen.  Even  the  unknown  hexa- 
nitro-benzene  would  only  contain  just  sufficient  oxygen 
for  its  complete  combustion.  Hence,  although  some  of  the 


EXPLOSIVE   COMPOUNDS  31 

nitro-compounds  can  be  detonated  alone,  they  are  almost 
invariably  used  in  conjunction  with  an  oxidizing  agent 
such  as  ammonium  nitrate,  although  for  certain  military 
purposes  picric  acid  and  trinitrotoluol  are  used  unmixed  with 
other  substances. 

The  organic  peroxides  are  also  explosives,  but  are  far  too 
unstable  to  be  of  any  practical  value,  and  the  same  applies 
to  the  ozonides.  These  latter  are  rich  in  oxygen ;  benzene 
ozonide,  for  example,  has  the  formula  C6H6O9,  and  would 
be  useful  were  it  not  for  their  extreme  instability. 

Of  the  inorganic  explosive  compounds,  lead  azide  is 
used  to  some  extent  for  detonators  as  a  substitute  for 
mercury  fulminate.  The  chlorates  being  formed  endo- 
thermically  from  the  chloride  and  oxygen  are  mildly  ex- 
plosive, and  are  used  in  some  explosive  mixtures,  e.g. 
Cheddite,  and  in  fireworks.  Ammonium  nitrate  can  be 
detonated  with  great  difficulty,  and  is  used  to  a  very  large 
extent.  Ammonium  perchlorate  can  also  be  detonated,  and 
is  an  ingredient  of  some  explosives.  Ammonium  bichromate 
is  also  an  explosive,  and  although  somewhat  expensive 
and  dangerous,  is  used  in  one  or  two  French  powders. 
The  capacity  of  all  these  ammonium  salts  to  explode  is  due 
to  the  acid  radical  oxidizing  the  ammonium  radical. 

NITROGLYCERINE 

The  term  "nitroglycerine"  is  chemically  incorrect,  the 
explosive  having  the  formula  CH2(ONO2)CH(ONO2)CH2- 
(ONO2),  and  being  therefore  glycerine  trinitrate.  The  term 
"nitroglycerine"  is,  however,  invariably  used  commercially, 
and  in  practice  is  frequently  abbreviated  to  N.G. 

Glycerine  for  nitration  should  be  almost  pufep^Good 
dynamite  glycerine  has  only  a  pale  amber  colgur,  and  its 
specific  gravity  should  be  not  less  than  1260.  jit  should  be 
almost  free  from  ash  and  contain  only  slight  traces  of  fatty 
acids,  aldehydes  (acrolein),  unsaponified  fat,  chlorides,  sul- 
phates, etc.  It  should  contain  no  sugar  or  glucose,  although 
these  are  sometimes  present  as  adulterants.  For  the  nitra- 
tion only  dearsenicated  or  non- arsenical  acids  should  be  used. 


32  EXPLOSIVES 

Nitration  is  invariably  carried  out  with  a  mixture  of  nitric 
and  sulphuric  acid,  and  nowadays  it  is  customary  to  make 
up  the  mixed  acids  with  oleum,  so  that  the  mixture  is^almost 
anhydrous,  but  contains  no  free  sulphuric  anhydride.  }  The 
use  of  oleum  is  not  essential,  but  is  a  matter  of  convenience. 
The  composition  of  the  mixed  acid  varies  in  different 
factories,  but  the  following  are  all  in  use  with  satisfactory 
results  :  — 

HNO3       ..         ..40  46-5  41*5 

H2S04      ..         ..  58-4  52-5  58-0 

H2O          ..         ..1-6  1-4  -5 


6  parts  of  mixed  acid  are  used  to  every  part  of 
glycerine. 

In  some  countries  nitration  is  carried  out  in  cast-iron 
jacketed  vessels  provided  with  a  mechanical  agitator. 
These  are  prohibited  in  almost  all  European  countries, 
lead  vessels  with  cooling  coils  being  used  and  agitation  being 
effected  by  compressed  air.  }ln  Great  Britain  nitration  must 
be  carried  on  at  a  temperature  not  exceeding  22°  C.,  but  in 
other  countries  the  limit  is  25°  C.,  or  even  30°  C.  The 
temperature  is  observed  by  means  of  two  thermometers, 
one  dipping  into  the  charge  and  one  suspended  above  the 
charge  and  registering  the  temperature  of  the  "  gas,"  i.e.  the 
air  which  is  being  forced  through  the  charge  for  agitating  it. 

Nitrating  House.  —  Two  types  of  nitrator  are  in  general 
use,  but  the  older  type  introduced  by  Nobel  (Fig.  6)  is  being 
rapidly  displaced  by  the  nitrator-  separator  of  Thomson, 
Nathan,  and  Rintoul.  *\  In  the  older  type  of  plant  the  charge 
of  acid  is  run  in  from  the  measuring  tank,  the  air  agitation 
and  cooling  water  turned  on  and  the  glycerine  then  sprayed 
in,  the  rate  at  which  the  glycerine  is  added  being  regulated 
so  as  to  maintain  a  temperature  of  22°  C.  During  the 
nitration  the  workman  watches  the  fumes  through  the 
window  A,  any  appearance  of  red  fumes  being  a  sign  of 
danger.  During  the  nitration  the  run-off  cock,  B,  is  tempo- 
rarily connected  by  means  of  a  movable  lead  gutter  with  a 
large  lead-lined  drowning  tank  outside  the  building,  so  that 


EXPLOSIVE   COMPOUNDS 


33 


should  the  charge  get  out  of  control  it  can  be  at  once  drowned. 
The  provision  of  a  drowning  tank  is  only  a  precautionary 


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o 

o 

o 

0 

o 

o 

o 

o 

o 

o 

o 

0 

o 

o 

o 

o 

Q 

0 

o 

o 

o 

o 

o 

o 

o 

o 

o 

0 

o 

o 

o 

o 

o 

0 

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0 

0 

o 

\p 

Q 

o 

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o 

o 

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o 

L^ 

S£ 

a 

==: 

0 

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T. 


FIG.  6.— Glycerine  Nitrator  (Old  Type). 


34  EXPLOSIVES 

measure,  as  if  a  suitable  quality  of  glycerine  is  used  and 
ordinary  care  taken  in  nitration  no  trouble  is  experienced. 
When  all  the  glycerine  has  been  added  the  charge  is  cooled 
to  15°  C.,  and  then  run  down  a  lead-lined  gutter  to  the 
separating  house.  The  size  of  charge  nitrated  varies  in 
different  factories  from  300  to  1500  Ibs.  of  glycerine.  The 
time  taken  depends  largely  on  the  temperature  of  the 
cooling  water,  and,  unless  a  refrigerating  plant  is  in  use, 
may  vary  from  half  an  hour  in  winter  to  two  hours  or  more 
in  summer.  When  nitration  is  finished  for  the  day  the 
nitrators  are  carefully  washed  out  and  allowed  to  stand 
overnight  with  water  pressure  on  the  coils.  This  latter 
is  a  precautionary  measure  to  detect  any  small  leakage. 
The  nitrators  require  to  be  dismantled  about  every  two 
months  for  examination  and  repairs. 

(Separating  House. — The  charge  from  the  nitrating 
house  is  received  in  lead  tanks  (Fig.  7)  and  allowed  to 
stand,  so  that  the  specifically  lighter  nitroglycerine  rises  to 
the  surface.  When  separation  is  complete  the  spent  acid 
is  run  off  from  the  bottom  cock,  A,  until  the  line  of  separa- 
tion is  seen  through  the  window  B.  The  nitroglycerine  is 
then  run  into  the  pre-wash  tanks  and  roughly  washed  with 
water  or  dilute  soda  solution.  Being  heavier  than  water, 
it  forms  the  lower  layer,  and  after  pre-washing  is  run  down  a 
gutter  to  the  wash  house  or  filter  house.  These  gutters 
must  be  j  acketed  with  warm  water  in  winter  time  to  prevent 
the  nitroglycerine  freezing.; 

The  waste  acid  from  the  separating  house  is  run  away  to 
the  after-separating  house,  where  it  is  allowed  to  stand  for 
two  or  three  days  in  order  that  separation  may  be  complete. 
The  oil  that  separates  is  skimmed  off  or  collected  by  dis- 
placement, and  carried  back  to  the  pre-wash  tank  in  gutta- 
percha  buckets.  The  waste  acid  is  pumped  to  the  acid 
department,  where  it  is  denitrated  with  steam  and  then 
concentrated.  As  a  rule  it  contains  10-12  percent,  of 
nitric  acid.  To  prevent  any  further  separation  of  nitro- 
glycerine it  is  advisable  to  dilute  it  with  one  or  two  per  cent, 
of  water,  and  not  to  allow  the  waste  acid  in  the  store  tanks 


EXPLOSIVE   COMPOUNDS 


35 


inf 


to  become  too  chilled  in  cold  weather.     In  any  case  it  should 
be  denitrated  as  soon  as  possible. 

Both  separating  and  after-separating  tanks  must  be 
provided  with  thermometers  and  with  compressed  air 
agitators  and  cooling  coils,  so  that  the  contents  can  be 
mixed  and  cooled  in  case  of  any  undue  rise  in  temperature 
due  to  decomposition  setting  in.  They  must  also  be  pro- 
vided with  drowning  tanks 
placed  outside  the  building. 

The  necessity  for  after- 
separation  can  be  avoided 
by  adding  3-5  per  cent,  of 
water  to  the  waste  acid. 
This  dissolves  the  globules 
of  nitroglycerine  and  pre- 
vents the  formation  of  further 
quantities  from  unchanged 
glycerine  or  glycerine  sul- 
phate. 

In  order  that  separation 
may  take  place  in  a  reason- 
able time,  the  mixed  acid 
used  for  nitration  should  be 
allowed  to  stand  for  several 
days  before  use  in  order  that 
suspended  matter,  such  as 
flue  dust,  iron  sulphate,  lead 
sulphate,  etc.,  may  settle 
OUt.  The  addition  of  Sodium  FlG.  7. —Separator  for  Nitroglycerine, 
fluoride  to  destroy  finely 

divided  silica  has  been  patented  (A.P.  804,817),  and  it  is 
claimed  that  a  great  saving  of  time  is  effected  by  its  use, 
only  about  'ooi  per  cent,  being  required.  On  the  other 
hand,  patents  have  been  taken  out  for  hastening  separation 
by  the  addition  of  siliceous  matter  such  as  china  clay 
(E.P.  i4,58612.  Pat.  Anm.  38,595  (1911))- 

*wash  and  Filter  House. — The  construction  of  wash 
tanks  varies  somewhat  in  different  factories,  but  the  best 


EXPLOSIVES 


type  is  that  shown  in  Fig.  8,  as  this  avoids  the  use  of  cocks, 
The  oil  is  agitated  with  the  water  or  soda  solution  by 
means  of  compressed  air  and  then  allowed  to  settle.  The 
supernatant  water  is  then  drawn  off  by  means  of  the  soft 
rubber  hose,  which  is  slowly  lowered.  The  oil  is  left  in  the 
tank  and  again  agitated  with  water  or  soda  solution,  and 
again  separated  as  before.  When  finally  neutral  the  oil 
is  drawn  off  by  lowering  the  outside  soft  rubber  hose.  In 


FIG.  8. — Wash  Tank  for  Nitroglycerine. 

another  type  of  wash  tank  the  lower  layer  of  oil  is  separated 
from  the  upper  aqueous  layer,  and  forced  into  another  tank 
on  the  same  level  by  adding  water. 

The  number  of  washings  required  is  usually  nine,  viz. 
three  water  washings  and  one  soda  washing  in  the  pre-wash 
tanks,  and  three  soda  washings  and  two  water  washings  in 
the  wash  house,  but  washing  must  be  continued  until  a 
satisfactory  heat  test  (over  ten  minutes)  is  obtained  (Section 
IX.).  The  strength  of  the  soda  solution  used  is  usually 
about  3  per  cent.,  and  all  water  must  be  at  about  22°  C. 
It  is  a  good  plan  to  do  the  final  washing  with  distilled  water, 


EXPLOSIVE   COMPOUNDS  37 

an  ample  supply  of  which  is  usually  available  at  no  cost 
from  the  condensed  steam  used  in  the  various  drying  stoves. 
Otherwise  softened  water  must  be  used. 

All  wash  waters  both  from  the  pre-wash  tanks  and  from 
the  wash  house  are  led  to  the  "  deposit  of  washings/' 
They  are  here  made  to  circulate  slowly  through  labyrinths 
of  lead  in  such  a  manner  that  they  pass  alternately  over 
and  under  the  partitions.  This  causes  them  to  deposit  any 
globules  of  oil  that  they  may  hold  in  suspension.  The  oil 
thus  deposited  is  collected  from  time  to  time,  and  carried 
back  in  gutta-percha  buckets  to  the  wash  house. 

After  washing  until  neutral  the  nitroglycerine  is  filtered 
through  sponges  sewn  up  in  flannel  bags,  in  order  to  remove 
flocculent  matter  and  suspended  water.  It  is  then  stored 
in  lead  tanks  in  carefully  warmed  houses,  but  is  almost 
invariably  used  within  36  hours  of  being  made. 

Nitrator  -  Separator.  —  This  form  of  nitrator  was 
patented  by  Thomson,  Nathan,  and  Rintoul  (E.P.  I5,98301, 
3020  °3),  and  is  described  in  the  Journal  of  the  Society  of 
Chemical  Industry,  1908,  page  193.  The  nitrator  is  shown 
in  Figs.  9  and  10,  and  the  charge  is  worked  as  follows. 
The  mixed  acid  is  introduced  and  nitration  carried  out 
as  described  on  page  32.  After  nitration,  however,  instead 
of  running  the  whole  charge  into  a  separate  vessel  for 
separation,  it  is  allowed  to  stand  for  a  few  minutes,  and 
waste  acid  from  a  previous  charge  then  slowly  introduced 
through  the  pipe  and  cock  C.  The  nitroglycerine  over- 
flows by  B  into  the  pre-wash  tank  situated  in  the  same 
building.  The  line  of  demarcation  of  the  mixed  acid  and 
oil  is  watched  through  the  window  A,  and  the  rate  of 
entrance  of  spent  acid  governed  so  that  this  remains  station- 
ary, the  nitroglycerine  overflowing  to  the  wash  tank  as 
rapidly  as  it  separates.  When  separation  is  complete  the 
nitrator  is  left  standing  full  of  acid  until  required  for  further 
use.  Any  further  nitroglycerine  that  has  separated  is  then 
removed  and  the  waste  acid  run  out  by  the  cock  D  to  the 
after-separators,  if  these  are  used,  but  when  the  nitrator- 
separator  is  used  it  is  customary  to  add  sufficient  water  to 


EXPLOSIVES 


0 

O 

o 

O 

o 
o 
o 
o 
o 
o 
o 


fcTWbl 
oooo 

oooo 

oooo 

oooo 

oooo 

oooo 

oooo 

oooo 

oooo 

oooo 

O  0  O.O 

—  * 

_^--* 

FIG.  9. — Nitta  tor-Separator. 


EXPLOSIVE   COMPOUNDS 


39 


the  spent  acid  to  prevent  any  further  separation  of  nitro- 
glycerine, and  thus  avoid  after-separation.  This  type  of 
nitrator  has  now  been  adopted  by  all  the  leading  works  in 
this  country,  as  it  has  the  following  advantages  : — 

(1)  No  cocks  are  used,  so  that  all  danger  of  an  explosion 
being  caused  by  the  friction  of  turning  a  cock  is  avoided. 

(2)  The  nitroglycerine  is  removed  as  soon  as  separated, 
so    that    the    duration    of 

time  in  which  it  is  in  con- 
tact with  acid  is  reduced 
to  a  minimum. 

(3)  Repairs  and  renewals 
are  much  les^.     The  older 
type  of  nitrator  has  to  be 
washed-out  every  day  after 
use,  and  the  dilution  of  the 
acid  which  remains  adher- 
ing to  the  lead   sets    up 
serious  corrosion.    It  is  for 
this  reason  that  the  nitrator 
has  to  be  dismantled  every 
two  months,  although  many 
authorities  state  that  the 
corrosion  is  due  to  fume. 
For  a  matter  of  fact  the 
lead  of  the  older  type  of 
nitrator  is  exposed  to  fume 

no  more  than  the  lead  of  the  nitrator-separator.  The 
nitrator-separator,  on  the  contrary,  remains  full  of  acid 
when  not  in  use,  so  that  corrosion  caused  by  the  dilution 
of  residual  acid  is  avoided.  The  first  nitrator-separator 
used  at  Waltham  Abbey  ran  for  2f  years  without  being 
dismantled,  and  was  then  found  to  be  in  perfectly  good 
condition,  no  repairs  of  any  sort  being  required. 

Nitroglycerine  is  a  colourless  oil  which  freezes  at  13*3°  C., 
but  exhibits  the  phenomenon  of  super-cooling  to  a  con- 
siderable extent.  When  in  the  frozen  state  it  is  less  easily 
detonated,  and  in  small  quantities  is  less  sensitive  to  shock, 


FIG.  10. — Nitra  tor-Separator.     (Plan 
showing  acid  inlets  and  outlets.) 


40  EXPLOSIVES 

although  in  bulk  it  is  probably  more  sensitive  when  frozen 
than  when  liquid. 

Nitroglycerine  has  a  marked  physiological  eff ect,  dilating 
the  blood-vessels  and  causing  violent  headache  and  sickness. 
It  is  rapidly  absorbed  through  the  skin  and  the  majority 
of  workers  suffer  severely  at  first,  although  they  usually 
become  immune  after  a  few  days.  The  best  remedy  for 
N.G.  headache  is  strong  black  coffee  or  aspirin. 

Nitroglycerine  is  very  sensitive  to  shock  and  is  exploded 
by  a  kilogram  weight  falling  4  cm.,  the  nitroglycerine  being 
confined  between  hardened  steel  surfaces. 

On  heating,  nitroglycerine  decomposes  slowly  below 
100°  C.  and  explodes  at  about  150°  C. 

On  the  manufacturing  scale  100  Ibs.  of  dynamite  glycerine 
yields  from  230  to  235  Ibs.  of  nitroglycerine.  The  cost  of 
manufacture  in  1914  was  about  6d.  per  Ib.  The  cost  of 
manufacture  at  two  Government  factories  during  the  period 
January-June,  1918,  was  just  under  £100  per  ton,  the 
glycerine  accounting  for  about  £40  and  the  nitric  acid  for 
about  £45  (C.T.J.,  1919,  p.  139). 

Attempts  have  been  made  to  use  dinitroglycerine  mixed 
with  glycerine  in  order  to  obtain  an  explosive  that  does  not 
freeze  so  readily,  but  not  much  success  has  been  achieved, 
as  the  dinitric  ester  is  soluble  in  water  and  forms  cryohydrates 
(D.R.P.  I7,575n,  181,385).  Much  greater  success  has  met 
the  use  of  dinitrochlorhydrin.  This  is  made  by  nitrating 
monochlorhydrin  in  exactly  the  same  way  that  glycerine 
.is  nitrated.  As,  however,  it  is  almost  solely  used  in 
conjunction  with  nitroglycerine,  it  is  more  usual  to  nitrate  a 
mixture  of  glycerine  and  monochlorhydrin  (S.5.,  1906,  227). 

Dinitrochlorhydrin  boils  with  slight  decomposition  at 
190°  C.,  and,  although  readily  detonated  by  fulminate,  is 
so  insensitive  to  shock  that  it  is  not  exploded  by  a  2  kg. 
weight  falling  2  metres.  It  can  only  be  frozen  with  great 
difficulty,  and  remains  liquid  at  —30°  C. 

Non-freezing  oils  have  also  been  obtained  by  nitrating 
mixtures  of  glycerine  and  diglycerine  (CH2OHCHOHCH2)2o» 
this  latter  being  formed  by  heating  glycerine  to  290°  C. 


EXPLOSIVE   COMPOUNDS  41 

with  or  without  a  trace  of  alkali  (5.5.,  1906,  231 ;  E.P.  957208) 
or  at  250°  C.  in  a  current  of  inert  gas  (B.P.  24,608 10). 

The  use  of  dinitroacetyl  glycerine  and  dinitroformin 
are  mentioned  in  D.R.P.  209,  943. 

Finally,  dinitroglycol  has  been  used  in  France.  It  is  a 
more  powerful  explosive  than  nitroglycerine,  and  it  is 
claimed  that  it  can  be  manufactured  at  a  lower  cost  (P.5., 
16,  72).  It  does  not  freeze  above  —20°  C. 

Interesting  results  have  been  obtained  from  a  study  of 
the  solubility  of  nitroglycerine  in  sulphuric  acid  of  various 
strengths,  and  in  sulphuric  acid  containing  nitric  acid. 
The  solubility  is  due  to  two  causes,  viz.  the  true  solubility 
of  nitroglycerine  as  such  and  the  solubility  due  to  the  de- 
composition of  the  explosive.  With  sulphuric  acid  alone 
the  solubility  rises  slowly  with  increasing  strength  of  acid 
until  an  acid  strength  of  about  50  per  cent,  is  reached. 
Then  the  rise  in  solubility  becomes  very  rapid,  the  curve 
being  almost  vertical  in  the  region  where  H2SO4=90  per  cent. 
Between  50  and  90  per  cent,  great  instability  is  exhibited, 
and  the  nitroglycerine  is  liable  to  undergo  spontaneous 
decomposition  with  uncontrollable  violence,  so  that  manu- 
facturing operations  must  be  so  adjusted  that  nitroglycerine 
is  not  brought  into  contact  with  acids  of  this  strength. 

With  sulphuric  acid  containing  water  and  nitric  acid 
in  the  proportion  i  :  1*1  the  case  is  somewhat  different, 
and  instability  is  most  marked  when  the  mixture  contains 
under  60  per  cent,  of  sulphuric  acid,  i.e.  contains  more  than 
40  per  cent,  of  nitric  acid  of  52  per  cent,  strength. 

The  curve  of  total  nitroglycerine  absorbed  in  acids  con- 
taining varying  percentages  of  sulphuric  acid  shows  a  very 
marked  peak  where  H2SO4=5o,  and  becomes  almost 
vertical  above  the  point  H2SO4=8o.  The  amount  of 
nitroglycerine  dissolved  as  such  also  becomes  very  steep 
when  H2SO4=8o,  but  the  peak  where  H2SO4=50  is  only 
very  slight,  showing  that  the  solubility  is  chiefly  due  to 
decomposition.  These  values  are  important  both  as  a 
guide  to  suitable  acid  mixtures  for  obtaining  a  good  yield 
and  also  as  showing  that  nitroglycerine  may  become 


42  EXPLOSIVES 

dangerous  through  violent  decomposition  when  in  contact 
with  acids  of  certain  strengths. 

Glycerine  is  invariably  obtained  from  natural  sources, 
viz.  from  fatty  oils,  and  is  a  by-product  from  the  soap 
industry.  Over  50  per  cent,  of  the  world's  production 
of  glycerine  is  used  in  the  manufacture  of  explosives,  the 
remainder  being  used  chiefly  for  medicinal  purposes.  In 
view  of  the  extremely  simple  chemical  structure  of  the 
glycerine  molecule,  it  is  curious  that  no  synthesis  has  yet 
been  devised  that  is  even  remotely  suited  for  use  on  a  large 
scale.  Proposals  have  been  made  to  carry  out  the  synthesis 
by  condensing  acetylene  with  methane  in  the  presence  of 
suitable  catalysts,  and  then  converting  the  butylene  thus 
obtained  into  glycerine  by  treatment  with  chlorine  and 
alakli  — 

CH  CH2  CH2C1  CH2OH 


CH  CH      ->    CHC1      ->    CHOH 

II  I  I 

CH2  CH2C1  CH2OH 

but  no  success  has  been  achieved,  as  the  reactions  are  not 
so  simple  as  they  appear. 

Glycerine  is  always  formed  as  a  by-product  in  the 
fermentation  of  sugar  by  yeast,  and  is  probably  formed  by 
the  auto-  digestion  of  the  yeast  cell.  A  process  based  on 
fermentation  would  therefore  not  seem  to  be  impossible, 
and  the  United  States  Government  claim  that  they  have 
evolved  such  a  process  and  have  proved  it  to  be  feasible 
on  a  manufacturing  scale.  No  details  have  been  made 
public,  but  the  process  has  been  communicated  to  the 
Allied  Governments. 

Prior  to  the  war  the  price  of  "  dynamite  glycerine  "  was 
variable,  but  in  the  neighbourhood  of  £100  per  ton,  about 
iof^.  per  lb.,  and  although  this  would  no  doubt  come  down 
considerably  with  increased  supplies,  still  the  demand  is 
so  great  that  a  sufficient  margin  would  remain  to  allow  a 
good  profit  on  a  synthetic  process  should  one  be  discovered. 

Possibly  glycerine  may  be  'displaced  in  the  future  to 


EXPLOSIVE   COMPOUNDS  43 

some  extent  by  glycol,  as  this  seems  somewhat  easier  to  obtain 
by  synthetic  means — 

CH  CH2  CH2Hlg  CH2OH 

III        ->     II          ->     I  ->     I 

CH  CH2  CH2Hlg  CH2OH 

The  best  results  are  obtained  by  using  bromine,  the 
yields  under  these  circumstances  being  said  to  be  almost 
theoretical.  The  capital  cost,  however,  is  very  heavy,  and 
the  unavoidable  mechanical  loss  which  takes  place  in  all 
manufacturing  operations  is  a  serious  item  when  an  ex- 
pensive material  such  as  bromine  is  involved,  so  that  should 
glycol  be  manufactured  extensively  by  this  method  it 
would  be  necessary  to  use  chlorine.  This,  owing  to  its 
lower  atomic  weight,  has  the  further  advantage  of  requiring 
considerably  less  alkali  for  the  final  hydrolysis.  Dinitro- 
glycol  is  quite  suitable  for  the  manufacture  of  explosives, 
and  its  use  is  actually  authorized  in  France  (see  page  41). 
It  contains  exactly  the  right  amount  of  oxygen  for  its  com- 
plete oxidation— 

CH2ONO2 

| 

CH2ONO2 

NITROCELLULOSE 

Cellulose  has  the  formula  (C6H10O5)n,  the  molecular 
weight  being  quite  unknown,  although  there  is  no  doubt  that 
the  molecule  is  of  great  complexity.  The  structure  is  also 
quite  unknown,  but  as  nitric  esters  containing  13*96  per 
cent,  of  nitrogen  can  be  obtained  it  is  probable  that  there 
are  three  hydroxyl  groups  reckoned  in  the  simple  mole- 
cule C6H10O5,  the  trinitric  ester  of  which  would  contain 
14-14  per  cent,  of  nitrogen.  It  may  be  said  at  once  that 
these  esters  with  high  nitrogen  content  are  unstable  and 
of  no  commercial  value,  as  it  is  almost  impossible  to  obtain 
stable  nitrocelluloses  containing  much  over  13-1  per  cent,  of 
nitrogen. 

Some  authorities  attempt  to  classify  nitrocelluloses  by 
ascribing  the  imaginary  formula  C24H40O20  to  cellulose,  but 


44  EXPLOSIVES 

the  cellulose  esters  as  at  present  known  are  undoubtedly 
mixtures,  and  it  is  much  more  scientific  to  characterize 
them  by  their  nitrogen  content  and  by  their  solubility  in 
ether-alcohol  (one  volume  ether  and  two  volumes  alcohol). 
Officially  in  this  country  guncotton  is  defined  as  nitrocellulose 
containing  over  12*3  per  cent,  of  nitrogen,  and  of  which  not 
more  than  15  per  cent,  is  soluble  in  alcohol-ether.  Esters 
containing  less  than  12-3  per  cent,  of  nitrogen,  and  more  or 
less  completely  soluble,  are  known  as  collodion  or  pyroxylin. 
In  factories  guncotton  is  generally  known  as  G.C.  and  collo- 
dion cotton  as  C.C.,  whereas  N.C.  denotes  nitrocelluloses  in 
general. 

The  whole  theory  and  practice  of  the  preparation  of 
nitrocellulose  rests  on  an  empirical  basis,  owing  to  the 
complete  absence  of  any  knowledge  of  the  structure  of  the 
cellulose  molecule.  Undoubtedly  all  forms  of  cellulose  are 
colloidal  in  nature,  but  to  what  extent  the  substance  known 
as  cellulose  represents  a  pure  compound  we  have  no  means 
of  ascertaining.  Probably  there  are  numerous  forms  of 
cellulose,  but  speculation  on  this  line  must  remain  guess- 
work in  our  present  state  of  knowledge.  In  the  manu- 
facture of  nitrocelluloses  the  chief  raw  materials  are  cotton 
waste,  used  chiefly  for  making  guncotton  and  collodions 
for  varnish  or  celluloid,  cotton  wadding  used  for  collodion 
for  blasting  explosives,  paper  used  for  various  purposes 
such  as  celluloid,  and  purified  wood  or  wood  pulp  used  for 
certain  smokeless  powders.  It  is  probable  that  great 
progress  has  been  made  in  the  use  of  wood  in  Germany 
owing  to  their  military  requirements  and  the  failure  of  the 
cotton  supply  through  the  Allied  blockade,  but  no  information 
on  this  point  is  as  yet  forthcoming. 

Cotton  waste  used  for  making  guncotton  undergoes 
several  processes  of  purification  before  it  is  fit  for  nitration. 
These  consist  in  extracting  with  solvents  and  scouring  with 
soda  to  remove  oil,  washing  and  bleaching.  This  preliminary 
treatment  is  carried  out  by  the  suppliers  and  not  by  the  explo- 
sives works.  As  delivered,  it  should  contain  under  8  per 
cent,  of  moisture  and  not  more  than  '4  per  cent,  of  oil.  It 


EXPLOSIVE   COMPOUNDS  45 

should  not  be  harsh  to  the  touch  or  friable  (over bleaching) 
and  should  only  produce  slight  reduction  when  boiled  with 
Fehling's  solution  (oxy cellulose) .  It  is  picked  over  by 
hand  to  remove  bits  of  string,  nails,  etc.,  and  then  run 
through  a  teasing  machine  to  loosen  knots,  dust  being  at 
the  same  time  removed  by  a  fan.  After  drying,  to  reduce 
the  moisture  to  i  per  cent,  or  less,  it  is  ready  for  nitration. 

Guncotton. — The  mixed  acid  used  for  manufacturing 
guncotton  in  this  country  (13  per  cent,  of  nitrogen)  has  the 
composition — 

HN03 23 

H2SO4 70 

H20 7 

In  the  old  Abel  process  the  cotton  in  lots  of  ij  Ibs.  was 
dipped  into  the  mixed  acid  contained  in  cast-iron  pans. 
After  five  minutes  it  was  lifted  out,  squeezed  by  hand  on 
an  iron  grating  and  then  placed  in  stoneware  pots  set  in  a 
trough  of  running  water.  Nitration  proceeded  for  12  hours, 
after  which  time  the  excess  of  acid  was  wrung  out  as  far 
as  possible  in  hydro-extractors  and  the  guncotton  drowned 
quickly  in  a  large  volume  of  cold  water .;  This  process^was 
later  modified  into  the  direct  dipping  process,  in  which  the 
cotton  is  digested  with  the  mixed  acid  for  from  8  to  24  hours 
at  20°  C.  in  water-cooled  iron  pans,  the  ratio  of  acid  to 
cotton  being  6  :  i.  Both  these  process^,  which  are  still  in 
use  on  the  Continent  and  in  some  collodion  works  in  this 
country,  were  wasteful  in  acid  and  injurious  to  the  workmen 
owing  to  the  fumes./  In  addition,  a  great  deal  of  labour 
was  involved  and  charges  fuming  off  were  frequent.  Indeed 
in  the  Abel  process  a  drop  of  perspiration  falling  on  to  a 
charge  when  digesting  was  frequently  sufficient  to  cause  it 
to  fume  off.  These  disadvantages  led  to  the  introduction 
of  the  displacement  process  by  Nathan  and  Thomson  (B.P. 
827803.  A.E.,  1906,  77),  by  which  great  economies  in 
material  and  labour  were  effected,  all  fumes  avoided,  and 
a  superior  product  obtained.  The  process  has  been  very 
generally  adopted  by  explosives  works  in  this  country. jmd 


46 


EXPLOSIVES 


is  coming  into  extensive  use  on  the  Continent  and  in 
America.  Up  to  the  present  it  has  not  been  generally 
used  for  the  manufacture  of  collodion,  but  by  selecting  a 
suitable  mixed  acid  there  would  seem  no  good  reason  why 
it  should  not  be  used  for  this  purpose,  and  no  doubt  the 
extensive  guncotton  plants  that  have  been  erected  for  war 


FIG.  ii. — Cotton  Nitrating  Pan  (Displacement  Process). 

purposes  will  be  diverted  in  this  direction,  the  collodion 
being  used  for  medicinal  and  photographic  purposes,  arti- 
ficial silk,  celluloid,  varnish,  aeroplane  dope,  etc. 

The  nitrator  is  shown  in  Fig.  n,  and  consists  of  a  shallow 
earthenware  pan,  3  ft.  6  in.  diameter,  10  in.  deep  at  the  sides 
and  12  in.  deep  at  the  run-off  cock  at  the  centre.  It  has  a 
false  bottom  of  perforated  stoneware  segments.  The  run-off 
cock  is  connected  with  the  mixed  acid  store  tanks,  waste 
acid  tanks,  and  with  a  drain,  and  four  nitrators  are  usually 


EXPLOSIVE   COMPOUNDS  47 

grouped  together  so  as  to  be  worked  as  one  unit.  In  carrying 
out  a  nitration  mixed  acid  (650  Ibs.)  is  allowed  to  run  into 
each  pan,  and  then  20  Ibs.  of  cotton  waste  added  in  single 
handfuls  and  quickly  pushed  under  the  surface  of  the  acid 
by  means  of  an  aluminium  fork.  During  this  process  the 
pan  is  covered  by  a  light  portable  aluminium  hood  connected 
with  a  fume  pipe  so  that  all  acid  fume  is  drawn  off.  When 
the  whole  of  the  cotton  has  been  added  it  is  covered  with 
loose  perforated  stoneware  segments,  on  to  the  surface  of 
which  a  layer  of  chilled  water  at  5°  C.  is  run  slowly.  This  seals 
the  plant  and  prevents  any  escape  of  fume:  Nitration  takes 
2  J  hours,  and  the  fuming  off  of  a  charge  is  almost  unknown. 
When  nitration  is  complete  the  waste  acid  is  run  off  at  the 
bottom  at  the  rate  of  about  one  gallon  per  minute,  and  at  the 
same  time  and  at  the  same  speed  cold  water  is  run  on  to  the 
top  perforated  plates.  Water  being  a  great  deal  lighter 
than  the  waste  acid,  the  line  of  demarcation  between  them 
remains  fairly  sharp  and  about  500  Ibs.  of  waste  acid  are 
recovered  in  a  state  fit  for  revivifying  with  nitric  acid  and 
oleum.  This  portion  of  the  waste  acid  has  the  com- 
position— 

HNO3 18 

H2S04 727 

H20     ..  ..  ..9*3 

the  rest  is  somewhat  weaker — 

HN03 18 

H2S04 61 

H2O 21 

and  is  denitrated  and  concentrated.  Displacement  takes 
about  three  hours,  and  the  loss  of  acid  is  only  about  I  per 
cent,  of  the  weight  of  the  guncotton  made.  The  yield  of 
guncotton  is  about  170  per  cent.  Up  to  the  present  these 
displacement  nitrators  have  always  been  constructed  of  the 
dimensions  given,  as  stoneware  vessels  of  large  size  are 
expensive  and  not  very  satisfactory.  There  would  seem  to 
be  no  reason,  however,  why  larger  vessels  should  not  be  * 
built  of  cast  iron  lined  with  acid-proof  stoneware  segments, 


48 


EXPLOSIVES 


of  enamelled  iron  or  of  ferro-silicon.  Naked  cast  iron  or  lead 
cannot  be  used,  as,  although  they  would  be  unattacked 
during  nitration,  they  would  be  seriously  affected  by  the  dilu- 
tion of  the  acid  during  the  later  stages  of  the  displacement. 
The  centrifugal  nitrating  process  is  used  extensively  in 
Germany  and  also  to  some  extent  in  this  country,  especially 
for  the  mauufacture  of  collodion  cotton  for  blasting  explo- 
sives. In  this  case  nitration  is  carried  on  in  a  centrifugal 


FIG.  12. — Nitrating  Centrifugal. 

machine  so  arranged  that  the  rotation  of  the  basket  causes 
the  acid  to  circulate  through  the  cotton.  A  simple  type  of 
nitrating  centrifugal  is  shown  diagrammatically  in  Fig.  12, 
the  circulation  of  the  acid  being  indicated  by  the  arrows. 
It  will  be  noticed  that  the  vertical  spindle  passes  through 
the  central  conical  part  of  the  outer  case  by  a  sleeve  situated 
well  above  the  acid  level,  and  is  attached  to  the  basket  at 
the  top  of  the  central  perforated  cone.  During  nitration 
the  machine  rotates  very  slowly,  but  when  nitration  is 
complete  the  excess  of  acid  is  run  off  and  the  machine  speeded 


EXPLOSIVE   COMPOUNDS  49 

up  so  as  to  wring  out  the  superfluous  acid.  This  wringing, 
however,  must  not  be  carried  too  far  or  there  will  be  con- 
siderable danger  of  the  charge  fuming  off,  and  this  applies 
to  all  processes  in  which  the  excess  of  acid  is  removed  by 
whizzing.  As  a  rule  the  acid  content  of  the  nitrated  cotton 
is  not  reduced  below  50-60  per  cent,  before  drowning.  The 
charge  for  a  centrifugal  machine  is  15-25  Ibs.  of  cotton  and 
750-1250  Ibs.  mixed  acid. 

The  composition  of  the  acid  used  for  making  collodion 
depends  on  the  duration  and  temperature  of  nitration, 
process  of  nitration  employed,  and  on  the  nature  of  the 
product  required.  The  viscosity  of  the  solutions  of  the 
collodion  depends  very  largely  on  the  temperature  at  which 
nitration  takes  place.  For  blasting  explosives  high  viscosity 
is  required,  so  that  nitration  is  carried  out  at  or  about  the 
ordinary  temperature.  A  suitable  mixed  acid  for  this 
purpose  is — 

HN03 25-0 

H2S04..          ...         57-5 

H20 17-5 

These   collodions   usually   contain  about    12  per   cent,   of 
nitrogen. 

For  smokeless  powders  the  viscosity  is  much  less  im- 
portant, nitrogen  content,  which  is  a  measure  of  power, 
being  the  important  point.  No  reliable  information  is 
available  as  to  the  acids  used  for  nitrating  cellulose  for 
sporting  powders,  but  the  United  States  military  powder 
is  made  with  an  acid  of  this  composition — 

HNO3 21-5 

H2S04 63-5 

H2O     . .          . .  . .          . .     15-0 

Nitration  is  carried  out  by  the  displacement  process  at 
a  temperature  of  30 °C.  and  takes  from  i  to  2 \  hours.  Seven 
hundred  pounds  of  acid  are  used  for  20  Ibs.  of  cotton,  and 
the  product  contains  about  12*7  per  cent,  of  nitrogen  and  is 
almost  completely  soluble  in  alcohol-ether.  A  similar  nitro- 
cellulose is  used  by  the  French  Army.  sThe  yield  is  155  per 
T.  4 


50  EXPLOSIVES 

cent.  For  varnishes  and  photographic  films  low  viscosity 
is  required,  and  hence  nitration  is  carried  out  at  a  higher 
temperature,  although  this  usually  entails  a  lower  yield. 
A  good  low  grade  pyroxylin  can  be  made  with  an  acid — 

HNO3 17 

H2S04 55 

H2O        28 

nitrating  for  15  minutes  at  45°-55°  C.  and  using  50  parts 
of  acid  to  each  part  of  cotton.  The  product  contains  about 
12*4  per  cent,  of  nitrogen,  and  the  yield  is  about  130  per  cent. 
Washing. — After  a  preliminary  wash  to  remove  the 
greater  part  of  the  acid  the  nitro-cotton  is  boiled  several 
times  with  water.  This  boiling  is  carried  out  in  pitch  pine 
vats  with  a  run-off  cock  below  a  perforated  false  bottom, 
heating  being  effected  by  direct  steam.  The  number  and 
duration  of  the  boilings  varies  at  different  factories,  but 
good  results  are  obtained  by  two  boils  of  twelve  hours  each, 
followed  by  five  of  four  hours  each  and  then  three  of  two 
hours  each,  the  object  of  the  long  boils  at  first  being  to 
hydrolyse  unstable  esters.  £  Collodion  cotton  for  blasting 
explosives  will  not  stand  such  drastic  treatment,  as  boiling 
spoils  the  viscosity  of  the  jelly  formed  with 'nitroglycerine. 
Hence  it  is  usual  only  to  wash  it  several  times  with  water 
near  the  boiling  point  A  Nitro-cotton  cannot  be  rendered 
stable  by  boiling  alone,  as  acid  gets  into  the  hollow  fibres 
and  cannot  be  removed  by  this  process.  The  only  way 
to  remove  this  is  by  the  pulping  process  introduced 
by  Abel.  After  boiling,  therefore,  the  cotton  is  removed 
to  pulpers  and  made  to  circulate  between  rapidly  re- 
volving knives  until  reduced  to  a  fine  pulp.  The  con- 
struction  of  a  pulper  is  shown  diagrammatically  in  Fig.  13. 
again  the  process  must  not  be  carried  too  far  with 
collodion  intended  for  blasting  explosives,  or  the  gelatinizing 
properties  will  be  spoilt.j  A  large  amount  of  water  is  used 
during  the  pulping  operation,  and  when  pulping  is  complete 
the  creamy  liquid  is  pumped  into  tanks  at  the  top  of  the 
building  and  then  made  to  flow  along  long  wooden  gutters 


EXPLOSIVE    COMPOUNDS  51 

lined  with  woolly  blanket  material.  The  woolly  material 
collects  a  large  amount  of  grit,  and  particles  of  iron  are 
collected  by  electro-magnets  placed  at  intervals.  The  pulp 
then  enters  a  large  timber  vat,  known  as  a  poacher,  fitted 
with  a  wooden  paddle,  where  it  is  allowed  to  settle  and  the 
supernatant  milky  water  drawn  off.  The  pulp  is  then  stirred 
up  with  more  water  and  again  allowed  to  settle.  It  is  usually 
given  three  washes  in  the  poacher,  and  is  then  removed 
to  hydro  extractors  and  as  much  of  the  water  as  possible 
extracted.  As  obtained  from  the  extractors  it  contains  25-35 
per  cent,  of  moisture,  and  in  this  state  is  perfectly  safe. 


FIG.  13. — Pulping  Machine  for  Nitrocellulose. 

Dry  nitrocellulose,  however,  is  very  easily  inflamed,  and  all 
operations  with  it  must  be  carried  out  in  danger  buildings. 
The  stoves  are  light  timber  structures  surrounded  by  earth 
mounds  and  certain  movable  trays  on  which  the  nitro- 
cellulose is  spread.  These  trays  may  be  constructed  of 
light  timber  frames  with  canvas  bottoms,  but  fine  copper 
gauze  or  zinc  sheet  is  much  better.  They  are  about  2  in. 
deep  and  must  be  earthed,  as  dry  nitrocellulose  is  very  easily 
electrified.  Heating  is  brought  about  by  blowing  in  warm 
air,  but  the  temperature  of  the  stove  must  not  exceed  40°  C. 
To  avoid,  nitrocellulose  dust  being  blown  about,  some  firms 
compress  the  wet  cotton  into  slabs  by  means  of  hydraulic 
presses  before  drying.  This  system  has  many  advantages, 


52  EXPLOSIVES 

although  drying  takes  somewhat  longer.  Only  moderate 
pressure  is  used  in  forming  the  slabs  so  that  they  are  easily 
broken  up  when  dry.  In  any  case,  as  dry  nitrocellulose  is 
much  more  dangerous  when  warm,  the  stoves  must  not  be 
unloaded  until  they  have  cooled. 

If  the  nitrocellulose  is  going  to  be  used  for  making 
smokeless  powder  by  gelatinization  with  alcohol  and  ether, 
or  if  it  is  going  to  be  used  for  making  a  solution  in  which 
alcohol  is  employed  as  a  solvent,  there  is  no  need  to  dry  it. 
Under  these  circumstances  it  is  packed  into"  cylinders  and 
alcohol  then  forced  through  it  in  a  downward  direction. 
The  first  runnings  are  pure  water,  followed  by  dilute  spirit 
which  is  afterwards  rectified.  The  last  runnings  are  stronger 
spirit,  and  are  used  for  the  first  washing  of  the  next  batch. 
The  process  is  very  similar  in  principle  to  the  displacement 
process  of  nitrating,  and  is  generally  known  as  "alcoholizing." 
The  average  cost  of  manufacturing  guncotton  (13  per 
cent,  nitrogen)  at  three  Government  factories  during  the 
period  January-June,  1918,  was  ^137*8  per  long  ton,  about 
is.  3^.  per  lb.,  this  amount  being  made  up  as  follows :  cotton 
waste  ^50*6,  nitric  acid  £44*5,  labour,  etc.,  £36*6,  sulphuric 
acid  £6-1  (C.T.J.,  1919,  p.  139). 


NlTROAROMATIC  COMPOUNDS 

Dinitrobenzole. — Although  mononitrobenzole  cannot  be 
exploded  either  by  a  blow  or  by  a  fulminate  detonator,  the 
dinitro-compound  is  sufficiently  unstable  to  be  exploded  by 
either  of  these  means,  although  only  with  difficulty,  explosion 
being  brought  about  by  a  two-kilogram  weight  falling  200 
cm.,  the  dinitrobenzole  being  confined  between  hardened 
steel  surfaces.  It  is  made  by  nitrating  nitrobenzole  with 
mixed  acids  at  100°  C.,  its  manufacture  being  fully  described 
in  the  volume  on  "  Coal  Tar  Dyes  and  Intermediates  "  in 
this  series.  The  pure  product  melts  at  91°  C.,  but  the 
commercial  article  at  8o°-85°  C. 

Dinitrotoluol  and  Trinitrotoluol.— Both  these  are  used 
extensively  in  the  manufacture  of  explosives,  especially  the 


EXPLOSIVE   COMPOUNDS  53 

latter.  Trinitrotoluol  (T.N.T.)  is  exploded  by  a  two-kilo- 
gram weight  falling  108  cm,,  and  is  fairly  readily  exploded 
by  fulminate  of  mercury.  In  the  pure  state  it  is  used  for 
naval  and  military  purposes  in  torpedo  charges  and  to  a  lesser 
extent  in  shells.  It  finds  its  chief  application,  however,  when 
mixed  with  nitrates,  especially  ammonium  nitrate,  for  shell 
filling  (amatol)  and  as  a  blasting  explosive./^  Although  T.N.T. 
can  be  obtained  from  toluol  in  one  step  this  process  is  very 
extravagant  in  acid,  and  consequently  the  manufacture  is 
invariably  carried  out  in  two  or  three  steps;  depending  to 
some  extent  on  the  quality  of  product  desired  and  on  what 
other  products  are  being  manufactured  simultaneously. 
In  spite  of  the  enormous  output  of  T.N.T.  for  war  purposes, 
it  is  doubtful  if  the  most  economical  process  for  use  under 
peace  conditions  has  yet  been  evolved.  This  is  due  to 
the  shortage  and  excessive  price  of  sulphuric  acid  having 
compelled  manufacturers  to  work  more  with  a  view  to 
economy  of  acid  and  oleum  than  with  a  view  to  minimum 
cost  of  production.  Under  present  circumstances  only 
about  2  Ibs.  of  T.N.T.  are  obtained  from  i  Ib.  of  toluol,  this 
corresponding  to  a  yield  of  about  77  per  cent,  of  theory. 
With  increased  supplies  of  oleum  available  it  will  probably 
be  found  more  economical  to  complete  the  final  nitration 
with  a  stronger  acid  and  a  correspondingly  lower  temperature, 
as  by  this  means  better  yields  will  be  obtained. 

In  carrying  out  the  nitration  in  two  steps,  toluol  is  first 
nitrated  to  mononitrotoluol  *  (M.N.T.)  and  this  then  further 
nitrated  to  T.N.T.  \  The  composition  of  the  mixed  acid 
used  for  the  final  nitration  depends  on  what  acids  are  avail- 
able for  mixing,  but  both  the  following  give  good  results. 
The  latter*,  however,  usually  requires  a  small  amount  of 
oleum — 

HNO3  16  18 

H2SO4  78  78 

H20    ..  ..6  4 

The  amount  of  mixed  acid  taken  is  such  that  it  contains 

*  For  details  seeBarnett,  "Coal  Tar  Dyes  an<l  Intermediates,"  in 
series,  p.  16, 


54 


EXPLOSIVES 


if  Ibs.  of  nitric  acid  for  every  pound  of  M.N.T.  to  be  nitrated. 
The  size  of  the  charge  varies  in  different  works,  but  by  using 


FIG.  14. — Nitrator  for  Nitroaromatic  Compounds 

12,000  Ibs.  of  mixed  acid  about  2000  Ibs.  of  T.N.T.  can  be 
made,  and  this  can  be  worked  conveniently  in  a  nitrator  of 


EXPLOSIVE  COMPOUNDS  55 

1000  gals,  working  capacity.  These  nitrators  are  made  of  cast 
iron  with  internal  lead  coils  for  heating  and  cooling,  and  are 
provided  with  an  efficient  mechanical  agitator  (Fig.  14).  In 
working  a  charge  the  mixed  acid  is  first  run  in  and  then  the 
M.N.T.  During  the  addition  of  the  latter  the  temperature  is 
not  allowed  to  rise  above  50°  C.  When  all  the  M.N.T.  has  been 
added  the  temperature  is  raised  at  the  rate  of  about  i°  C. 
every  two  minutes.  At  about  70°  C.  there  is  considerable 
evolution  of  heat,  and  care  must  be  taken  to  check  this  by 
turning  water  into  the  coils.  The  charge  is  generally  cooked 
for  i  hour  at  100°  C.,  and  the  temperature  then  slowly  raised 
to  120°  C.  and  maintained  at  this  point  until  nitration  is 
complete.  This  generally  takes  about  J  hour,  and  is  ascer- 
tained by  taking  a  sample  and  determining  the  setting 
point.  The  charge  is  then  cooled  to  85°  C.,  and  about  f  gallon 
of  water  for  every  hundred  pounds  of  mixed  acid  used  run 
in.  The  object  of  this  is  to  reduce  the  solubility  of  the 
T.N.T.  in  the  spent  acid  (D.R.P.  254,754).  During  the 
addition  of  the  water  the  heating  up  of  the  charge  must  be 
carefully  checked  and  the  temperature  not  allowed  to  rise 
above  100°  C.  The  charge  is  then  again  cooled  to  85°  C., 
the  agitator  stopped  and  separation  allowed  to  take  place 
for  an  hour.  The  lower  layer  of  spent  acid  is  then  drawn  off 
and  the  supernatant  T.N.T.  run  off  into  a  tank  of  boiling 
water  for  washing.  It  must  be  washed  free  of  acid,  and  on 
no  account  must  any  alkali  be  used,  as  if  so  the  T.N.T. 
becomes  very  sensitive.  Usually  four  washes  suffice  to 
remove  all  the  acid,  after  which  the  T.N.T.  is  dried  by  heating 
to  105°  C.  and  then  either  cast  in  shallow  trays  or  flaked 
on  an  internally  water-cooled  revolving  drum.  Instead  of 
adding  water  to  the  charge  after  nitration,  dilute  sulphuric 
acid  obtained  from  the  vitriol  concentrating  plant  can  be 
conveniently  used. 

The  waste  acid  from  the  trinitration  contains  consider- 
able quantities  of  T.N.T.  in  solution.  This  can  be  recovered 
by  agitating  it  at  80°  C.  with  the  M.N.T.  to  be  used  for 
the  next  charge,  in  which  case  any  nitric  acid  present  is 
used  up  with  the  formation  of  a  small  quantity  of  dinitro- 


56  EXPLOSIVES 

toluol.  In  this  case  the  final  waste  acid  will  contain  about 
3  per  cent,  of  nitrous  acid,  and  is  denitrated  and  concentrated 
for  further  use.  In  some  works,  however,  the  T.N.T.  spent 
acid  is  revivified  by  the  addition  of  nitric  acid  and  then 
used  for  making  M.N.T.  The  T.N.T.  made  by  this  process 
has  a  setting  point  of  about  76°  C. 

The  three-stage  process  is  somewhat  more  complicated, 
but  is  frequently  used  by  those  works  which  make  m- 
toluylenediamine.  As  before,  the  toluol  is  first  nitrated  to 
M.N.T.  This  is  then  converted  into  the  dinitro-compound  by 
treatment  with  an  acid  of  the  composition— 

HNO3 30 

H2S04  64 

H20 6 

nitration  being  carried  on  at  60°  C.  and  the  charge  finally 
cooked  at  80°  C.  The  dinitro-compound  can  then  be 
directly  nitrated  to  T.N.T.,  or  it  can  be  roughly  separated 
into  fractions  of  high  and  low  setting  point.  This  is  done 
by  draining  in  on  fine  mesh  wire  gauze  trays  at  a  temperature 
near  its  setting  point,  when  most  of  the  lower  melting  fractions 
run  off,  the  last  being  got  rid  of  by  whizzing.  If  the  residue 
is  then  nitrated,  T.N.T.  with  a  setting  point  of  80°  C.  is 
obtained.  The  oil  can  also  be  nitrated,  and  for  this  purpose 
Bscales  recommends  an  acid  of  the  composition— 

HN03         10-2 

H2SO4         82-2 

H20  7-6 

allowing  a  ratio  of  acid  to  dinitro-compound  of  2-8:1. 
The  setting  point  of  the  T.N.T.  thus  obtained  is  72°-74°  C. 
Those  qualities  of  T.N.T.  that  have  low  setting  points  are 
obviously  mixtures  of  various  isomeric  trinitrotoluenes  with 
some  dinitrotoluene. 

For  the  manufacture  of  blasting  explosives  the  setting 
point  of  T.N.T.  is  not  a  matter  of  importance,  but  for  deto- 
nating fuze  and  certain  military  purposes  in  which  the 
explosive  is  to  be  used  unmixed  with  nitrate  it  is  necessary 
to  employ  almost  pure  sym- trinitrotoluene  (M.P.  81-9)  in 


EXPLOSIVE   COMPOUNDS  57 

order  to  secure  complete  detonation.  For  this  purpose  the 
crude  T.N.T.  can  be  crystallized  from  alcohol  containing 
20  per  cent,  of  benzole,  from  onitrotoluol  (B.P.  I7,oo314)  or 
from  sulphuric  acid  monohydrate  (D.R.P.  237,738).  The 
setting  point  can  also  be  raised  by  washing  with  alcohol  or 
boiling  sodium  sulphite  solution,  or  by  allowing  the  crude 
product  to  drain  on  wire  gauze  in  stoves  maintained  at  a 
temperature  approximating  to  its  setting  point. 

When  organic  solvents  are  employed  in  its  purification 
the  residue  left  on  distillation  consists  of  a  mixture  of  di- 
and  tri-nitrotoluols.  On  nitration  it  yields  a  product  which 
remains  liquid  at  the  ordinary  temperature  and  is  much 
used  for  manufacturing  blasting  explosives,  especially  non- 
freezing  jellies,  as  it  mixes  very  readily  with  nitroglycerine. 
The  first  liquid  product  of  this  nature  was  manufactured 
by  J.  W.  Iveitch  &  Co.,  of  Huddersfield,  and  sold  as  "  liquid 
trinitrotoluol."  The  method  of  manufacture  is  a  trade 
secret,  and  although  other  firms  have  produced  similar 
liquids,  they  have  not  the  same  capacity  for  remaining  fluid 
and  usually  become  pasty  on  standing.  Trinitrotoluol, 
like  all  other  aromatic  nitro-compounds,  has  a  decidedly 
toxic  effect  on  those  working  with  it.  The  preliminary 
symptom  is  a  rash  which  appears  chiefly  on  the  arms  and 
may  be  followed  by  toxic  jaundice,  several  fatalities  having 
occurred  from  this  cause.  The  trouble  is  most  marked  during 
the  summer  months,  and  some  individuals  are  much  more 
sensitive  than  others.  Those  that  are  sensitive  should  not 
be  allowed  to  continue  working,  and  any  worker  who  shows 
signs  of  rash  should  at  once  be  given  a  change  of  work 
until  these  symptoms  have  subsided.  In  Great  Britain  there 
is  a  statutory  obligation  to  provide  baths,  special  clothes,  and 
rubber  gloves  for  those  handling  T.N.T.  and  kindred  com- 
pounds. As  regards  rubber  gloves,  the  author's  experience  is 
that  they  do  more  harm  than  good,  as  the  interior  gets  soiled 
when  taking  off,  and  thereafter  the  sweating  of  the  hands 
that  they  induce  causes  T.N.T.  to  be  more  readily  absorbed 
through  the  skin.  Closely  woven  cotton  gloves  or  chamois 
leather  gloves  are  more  satisfactory,  as  they  can  be  washed 


58  EXPLOSIVES 

after  each  day's  work  if  necessary.  Probably  the  best 
preventive  methods  will  be  found  to  lie  in  ample  ventila- 
tion, prevention  of  dust,  and  the  artificial  cooling  of  the 
work-rooms  during  warm  weather.  When  possible,  workers 
should  be  given  a  change  of  employment  at  regular  intervals. 
Under  the  provisions  of  the  Factory  Act  they  must  be 
medically  examined  at  frequent  intervals. 

Trinitrotoluol  is  known  under  various  trade  names  such 
as  trotyl,  tritol,  triolite,  but  most  usually  by  the  initials 
T.N.T.  Until  recently  it  was  specially  exempted  from  treat- 
ment as  an  explosive  by  an  Order  in  Council  made  under 
the  Explosives  Act.  The  numerous  accidents  that  occurred 
during  the  war  have  led  to  the  withdrawal  of  this  exemp- 
tion, and  trinitrotoluol  must  now  be  manufactured  under 
"  danger  "  conditions.  The  average  cost  of  manufacture  of 
crude  T.N.T.  (setting  point  j6°-j8°  C.)  at  six  Government 
factories  during  the  period  January- June,  1918,  was  £110 
per  ton,  the  average  consumption  of  toluol  being  -491  ton 
per  ton  of  T.N.T.  These  figures  must,  however,  be  accepted 
with  some  reserve,  for  whereas  toluol,  acid,  and  nitrate 
seem  to  be  reckoned  in  long  tons  (2240  Ibs.)  it  is  not  stated 
whether  T.N.T.  is  reckoned  in  long  tons  or  in  short  tons 
(2000  Ibs.),  the  latter  being  almost  invariably  employed 
when  dealing  with  explosives  (C.T.J.,  1919,  p.  117). 

Picric  Acid  (Trinitrophenol). — Under  the  names  of 
Ivyddite,  Melinite,  etc.,  'picric  acid  was  for  many  years  the 
standard  shell-filling  used  by  almost  all  the  Powers,  but 
during  recent  years  it  has  largely  been  replaced  by  the 
cheaper,  safer,  and  more  convenient  T.N.T.  The  great 
disadvantage  of  picric  acid  lies  in  its  acidic  character  and  its 
capacity  for  forming  highly  sensitive  salts,  especially  with 
the  heavy  metals,  the  lead  salt  being  the  most  dangerous. 
Picric  acid  cannot  safely  be  mixed  with  nitrates  such  as 
ammonium  nitrate,  as  owing  to  its  strongly  acid  character 
a  certain  amount  of  free  nitric  acid  would  be  liberated 
should  the  explosive  become  damp.  Its  use  is  confined 
to  military  purposes,  and  it  will  probably  be  completely 
displaced  by  T.N.T.  at  an  early  date. 


'EXPLOSIVE    COMPOUNDS  59 

Picric  acid  was  originally  manufactured  by  direct  nitra- 
tion of  phenol,  but  this  process  is  never  carried  on  now, 
although  in  1900  a  process  for  nitrating  phenol  in  paraffin 
was  described  (B.P.  16,628 °°)  and  good  results  claimed. 
The  usual  process  is  based  on  the  sulphonation  of  phenol 
to  the  monosulphonic  acid  with  subsequent  nitration  and 
simultaneous  replacement  of  the  sulphonic  acid  group.  The 
sulphonation  is  carried  out  with  4  parts  of  sulphuric  acid  of 
98  per  cent,  strength  at  ioo°-io5°.  Another  four  parts  of 
sulphuric  acid  are  then  added  and  the  melt  run  into  a  nitrator 
and  cooled  to  20°  C.  The  nitrator  may  be  made  of  cast 
iron,  but  enamelled  iron  is  preferable.  Nitration  is  brought 
about  by  the  slow  addition  of  mixed  acid  composed  of  equal 
parts  of  concentrated  sulphuric  acid  and  nitric  acid  of  61  per 
cent,  strength.  At  first  the  temperature  is  kept  below 
40°  C.,  but  after  half  the  mixed  acid  has  been  added  the 
temperature  is  slowly  increased  to  70°-8o°  C.  The  charge 
is  then  run  into  a  series  of  stoneware  pots  and  diluted  with 
an  equal  volume  of  water.  On  cooling  the  picric  acid 
crystallizes  out  and  is  filtered  off,  washed,  whizzed,  and 
finally  dried  at  a  low  temperature,  usually  35°  C. 

A  more  modern  process  avoids  the  use  of  phenol,  chlor- 
benzole  being  used  as  the  starting  out  point.  This  is  first 
nitrated  to  the  dinitro-compound,  which  on  boiling  with 
soda  gives  dinitrophenol.*  This  latter  is  readily  nitrated 
to  picric  acid,  but  details  of  the  nitrating  process  are  not 
available  at  present.  This  is  probably  the  best  process,  and 
is  likely  to  replace  the  older  process  if  picric  acid  continues 
to  find  use  as  an  explosive.  The  cost  of  manufacture  of 
picric  acid  at  H.M.  Factory,  Greetland,  during  the  period 
January-June,  1918,  was  £1847  Per  l°nS  ton>  a^out  is.  8d. 
per  Ib.  The  process  used  was  the  nitration  of  phenol 
sulphonic  acid  (C.T.J.,  1919,  p.  162). 

Picric  acid  melts  at  122-6°  C. 

Tetranitroaniline. — This  was  first  obtained  by  Flursheim 
in  1910  by  nitrating  w-nitraniline  or  certain  near  derivatives 

*  For  details  see  Barnett,  "Coal  Tar  Dyes  and  Intermediates,"  in  this 
series,  pages  18  and  66. 


60  EXPLOSIVES 

of  w-nitraniline  (E.P.  322410).  The  patentee  describes  the 
nitration  of  w-nitraniline  as  follows  :  "  One  part  of  meta- 
nitro- aniline  is  dissolved  in  36  parts  of  strong  sulphuric 
acid  (either  concentrated  acid  or  monohydrated  or  fuming 
acid)  at  the  ordinary  temperature  or  with  external  cooling, 
2j  parts  of  sodium  nitrate  are  then  added,  and  the  mass  is 
allowed  to  remain  at  the  ordinary  temperature  or  at  a  lower 
or  only  slightly  higher  temperature  for  several  days."  He 
also  states  that  the  nitration  can  be  carried  out  by  heating 
to  70°  C.  and  then  finally,  after  the  reaction  has  subsided, 
to  100°  C.  It  will  be  seen  that  a  very  excessive  amount  of 
sulphuric  acid  is  required,  and  the  cost  of  the  process  could 
only  be  kept  within  reasonable  bounds  by  using  the  spent 
acid  for  other  purposes.  The  compound  has  been  used  for 
detonator  compositions,  but  tetranitromethyl  aniline  has 
been  found  more  suitable  for  this  purpose. 

Tetranitromethyl    Aniline. — This   is   really   trinitro- 

methyl  phenylnitramine  CH3N<  6  ^Q         ,  and  is  known 

usually  as  tetryl  or  tetralite.  It  is  manufactured  by  nitrating 
dimethyl  aniline,  one  methyl  group  being  simultaneously 
oxidized.  The  process  is  described  by  Escales  ("  Nitro- 
sprengstoffe  ")  as  follows  : — 

One  hundred  kilos,  of  dimethyl  aniline  are  slowly  added 
to  1000  kilos,  of  well-cooled  concentrated  sulphuric  acid  of 
97-98  per  cent,  strength.  A  pale  brown  coloured  solution 
is  obtained,  but  it  must  not  be  too  dark  and  must  remain 
transparent.  As  the  solution  decomposes  on  standing  the 
nitration  should  be  effected  as  soon  as  possible.  This  is 
brought  about  by  running  the  solution  slowly  into  530  kilos, 
of  nitric  acid  of  87  per  cent,  strength  which  has  previously 
been  warmed  to  40°  C.  The  strength  of  the  nitric  acid  is 
important,  as  if  a  stronger  acid  is  used  the  product  separates 
in  large  crystals  which  are  difficult  to  wash.  During  the 
addition  of  the  dimethyl  aniline  solution  the  temperature 
at  first  is  not  allowed  to  exceed  44°  C.,  but  after  two- thirds 
has  been  added  it  is  allowed  to  rise  to  55°  C.,  and  when  the 
addition  is  complete  the  charge  is  cooked  for  two  hours  at 


EXPLOSIVE   COMPOUNDS  61 

this  temperature  and  is  then  cooled  and  allowed  to  stand 
overnight.  The  nitro-compound  crystallizes  out  and  the 
majority  of  the  spent  acid  can  be  run  off.  On  the  average 
this  has  the  composition — 

HNO3 11-05 

H2SO4 74-04 

H2O 12-09 

NO2 2-58 

Nitro-compounds        . .          . .  -24 

The  nitro-compound  is  then  collected  on  niters,  and  after 
washing  first  with  dilute  sulphuric  acid  and  then  with  water 
is  dried.  The  yield  of  the  crude  product  is  210  kg.,  but  it  is 
unstable  and  should  be  purified  at  once  by  recrystallization 
from  benzole.  The  benzole  is  recovered  from  the  liquors  by 
distillation,  and  to  avoid  danger  of  the  residue  exploding  it  is 
best  to  add  a  large  volume  of  water  before  commencing  the 
distillation.  These  residues  are  quite  valueless  and  are  burnt. 

Tetryl  jtnelts  at  I29°-I30°  C.  and  is  very  poisonous.  Up 
to  the  present  it  has  only  found  application  for  detonators 
or  shell  fuzes,  but  its  use  as  a  shell  filling  or  as  an  ingredient 
in  blasting  explosives  has  been  proposed.  During  the  period 
January-June,  1918,  145*6  tons  of  tetryl  were  manufactured 
at  H.M.  Factory,  Queensferry,  at  the  average  cost  of  £297*4 
per  (short?)  ton,  the  consumption  of  dimethyl  aniline  being 
•546  (long  ?)  tons  per  (short  ?)  ton  of  tetryl  produced  (C.T.J., 
1919,  p.  162). 

Pentanitromethyl  aniline  (tetranitromethylphenyl  nitra- 
mine)  has  been  described  (B.P.  3907 10),  but  does  not  seem 
to  have  found  any  application. 

MISCELLANEOUS  COMPOUNDS 

The  following  compounds  have  been  proposed  for  use  as 
explosives  or  as  ingredients  in  the  manufacture  of  explosives, 
and  although  not  in  general  use  they  are  worthy  of  short 
notice  with  a  view  to  possible  future  developments  : — 

Nitromethane,  CH3N02. — A  stable  liquid  boiling  un- 
decomposed  at  101°  C.  It  is  readily  obtained  by  the  action 
of  sodium  nitrite  on  chloracetic  acid  (B.,  42,  3438),  and  owing 


62  EXPLOSIVES 

to  its  low  molecular  weight  would  be  useful  as  a  means  of 
lowering  the  freezing  point  of  nitroglycerine.  Its  high  cost 
precludes  its  use  at  present,  but  experiments  carried  out  by 
the  author  indicate  that  the  yields  could  be  greatly  improved. 

Tetranitromethane  C(N02)4.— This  freezes  at  13°  C. 
and  boils  undecomposed  at  126°  C.  Owing  to  its  large 
content  of  oxygen  it  would  be  a  most  valuable  ingredient. 
Several  processes  have  been  described  for  manufacturing 
it  by  the  action  of  nitric  acid  or  nitric  anhydride  on  acetic 
anhydride  (D.R.P.  211,198,  211,199,  224,057)  or  on  nitro- 
aromatic  compounds  such  as  picric  acid  (D.R.P.  184,229), 
but  it  is  doubtful  if  any  of  them  are  yet  technically  possible. 
Tetranitromethane  is  very  toxic. 

Nitro-sugars. — These  have  been  studied  with  a  view  to 
their  use  in  detonators.  As  a  class  they  are  soluble  in  water 
and  hence  their  isolation  is  troublesome.  They  can  be 
purified  by  crystallization  from  alcohol,  but  are  too  sensitive 
and  unstable  for  use  (B.,  1898,  68-90). 

Nitro-mannitol. — Mannitol  gives  a  hexanitrate  which 
is  insoluble  in  water  and  can  be  crystallized  from  alcohol. 
It  melts  at  112°  C.  and  is  comparatively  stable.  Several 
attempts  have  been  made  to  employ  it  in  detonators,  but  with- 
out success  so  far.  It  is,  however,  worthy  of  further  attention. 

Nitro-starch. — Many  attempts  have  been  made  to 
employ  nitro-starch  as  an  ingredient  in  explosive  mixtures, 
but  up  to  the  present  no  marked  success  has  been  obtained. 
Starch  is  troublesome  to  nitrate,  as  it  balls  together,  and  the 
only  satisfactory  method  is  to  dissolve  it  in  nitric  acid  and 
then  spray  the  solution  into  sulphuric  acid  or  mixed  acid. 
So  far  it  has  been  found  impossible  to  stabilize  the  product 
on  an  industrial  scale,  but  as  a  stable  nitro-starch  with 
14*04  per  cent,  of  nitrogen  has  been  obtained  in  the  laboratory 
by  elaborate  treatment  with  organic  solvents  it  must  be 
concluded  that  the  instability  is  due  to  impurities.  Nitro- 
starch  is  soluble  in  nitroglycerine,  but  does  not  gelatinize  it. 
For  further  information  see  S.S.,  1910,  82. 

Hexanitrodiphenylamine. — This  has  been  used  in 
Germany  as  a  charge  for  floating  mines.  It  is  made  b}^  the 


EXPLOSIVE   COMPOUNDS  63 

nitration  of  diphenylamine  or  by  condensing  chlordinitro- 
benzole  with  aniline  and  then  nitrating  the  dinitrodiphenyl- 
amine  thus  obtained.  It  has  the  objectionable  property  of 
being  an  acid  and  is  extremely  poisonous,  so  that  its  use  is 
not  likely  to  become  general  (S.S.,  1910,  15  ;  1913,  205,  231  ; 
D.R.P.  86,295). 

Hexanitrodiphenyl  Sulphide  (Picryl  sulphide).— This 
can  be  obtained  by  the  action  of  sodium  thiosulphate  on 
picryl  chloride  (B.P.  i8,35313).  It  is  very  stable,  non- 
poisonous,  and  does  not  stain  yellow.  It  is  decidedly  more 
powerful  than  picric  acid  and  about  10  per  cent,  stronger 
than  trinitrotoluol.  It  has  been  proposed  for  use  in 
detonators  and  as  a  shell-filling.  In  connection  with  the 
latter,  and  in  view  of  the  use  of  gas  in  warfare  by  Germany, 
it  is  interesting  to  note  that  the  patentee  (Carl  Hartmann, 
Schlebusch)  claims  that  "  the  free  sulphurous  acid  contained 
in  the  fumes  on  the  detonation  of  a  striking  shell  renders  the 
continuance  in  a  closed  space,  such  as  casemates,  holds  of 
vessels,  etc.,  impossible  "  (E.P.  i8,35413) .  Unfortunately  the 
compound  is  expensive  to  produce,  as  picryl  chloride  can  only 
be  obtained  by  the  nitration  of  chlorbenzole  by  using  excessive 
amounts  of  acid.  This  might  be  remedied  to  some  extent 
by  fortifying  the  waste  acid  from  the  trinitration  and  then 
using  it  for  mono-  or  di-nitration.  The  corresponding  sulphone 
is  obtained  by  oxidation  with  nitric  acid  (D.R.P.  269,826). 

Hexanitrodiphenyl  Oxide.— The  symmetrical  com- 
pound (picric  anhydride)  has  not  been  described,  but  an  un- 
symmetrical  compound  is  obtained  by  condensing  i-chlor- 
2-4-dinitro-benzole  with  w-nitro-phenol  and  then  nitrating 
(D.R.P.  281,053).  It  is  a  stable  compound  of  about  the 
same  power  as  picric  acid. 

Hexanitro-oxanilide.— This  can  be  obtained  by  nitrat- 
ing oxanilide  (F.P.  391,106).  It  is  a  stable  compound 
melting  at  295°-300°  C.,  and  is  about  as  powerful  as  tri- 
nitrotoluol. Its  temperature  of  explosion  is  rather  low,  and 
hence  it  may  find  useful  application  as  an  ingredient  of 
permitted  explosives  for  use  in  fiery  mines. 

Hexanitrodiphenyl. — A  stable   explosive  obtained  by 


64  EXPLOSIVES 

the  action  of  copper  powder  on  picryl  chloride.  It  is  too 
expensive  for  general  use,  but  may  find  application  for 
detonators  (F.P.  i8,33314). 

Spent  Acids. — The  manufacture  and  concentration  of 
nitric  and  sulphuric  acids  is  treated  in  another  volume  in 
this  series,*  but  although  the  recovery  of  spent  acids  from 
nitration  operations  is  carried  out  by  similar  means  it  is 
accompanied  by  certain  difficulties,  due  chiefly  to  the  organic 
impurities  present.  The  recovery  of  spent  acids  from  the 
manufacture  of  aliphatic  nitric  esters  is  the  most  simple,  as 
these  acids  are  fairly  readily  burnt  clean.  In  dealing  with 
nitrocellulose  waste  acid  the  strongest  portion  is  revivified 
for  further  use  by  the  addition  of  oleum  and  nitric 
acid,  and  the  nitric  acid  then  recovered  from  the  remainder 
by  distillation.  The  residual  sulphuric  acid  still  contains 
2-3  per  cent,  of  nitrous  acid  which  cannot  be  removed  by 
distillation  and  it  is  denitrated  by  steam,  the  nitrous  acid 
being  recovered  as  nitric  acid  in  towers.  The  removal  of 
this  nitrous  acid  is  absolutely  necessary,  not  only  on  the 
grounds  of  economy,  but  also  to  avoid  trouble  with  the 
lead  work  of  the  concentration  plant.  The  denitrated  acid 
is  finally  concentrated,  this  being  almost  invariably  done 
in  this  country  in  the  Kessler  plant,  although  the  Gaillard 
tower  is  in  use  by  at  least  one  big  firm,  and  cascade  plants 
are  also  used. 

Nitroglycerine  waste  acids  are  not  distilled,  but  are 
denitrated  with  steam  and  then  concentrated.  lyike  nitro- 
cellulose waste  acids,  this  is  easily  accomplished  and  is  usually 
carried  out  in  the  Kessler  plant. 

Spent  acids  from  aromatic  nitrations  are  much  more 
difficult  to  deal  with  owing  to  the  more  stable  nature  of 
the  organic  impurities  which  they  contain.  In  addition 
the  separation  of  the  nitro-compounds  is  slow  and  in  fact 
usually  continues  for  several  days  or  even  weeks,  although 
the  amount  that  separates  is  usually  comparatively  small 
and  hardly  worth  recovering.  The  acids  usually  contain 
little  or  no  nitric  acid,  but  from  3  to  4  per  cent,  of  nitrous 
*  Partington,  "The  Alkali  Industry,"  in  this  series. 


EXPLOSIVE   COMPOUNDS  65 

acid,  and  hence  denitration  must  be  brought  about  by 
steam.  A  certain  proportion  of  the  organic  matter  is 
volatilized  by  this  means,  and  as  it  becomes  further  nitrated 
it  sets  at  a  comparatively  high  temperature  and  causes 
great  trouble  in  the  condensers  and  towers.  This  is  best 
remedied  by  using  vety  capacious  condensers  and  keeping 
the  part  of  them  nearest  the  towers  at  about  5o°-6o°  C.,  but 
facilities  must  be  provided  for  cleaning  out  solid  matter, 
and  steam  laid  on  so  that  the  whole  plant  can  be  heated  up 
should  signs  of  a  stoppage  appear.  The  denitrated  acid 
still  contains  a  large  quantity  of  organic  matter,  and  this 
tends  to  separate  more  readily  owing  to  the  greater  dilution 
of  the  acid.  Provision  must  therefore  be  made  for  collecting 
any  that  separates,  as  otherwise  it  may  catch  fire  in  the 
concentration  plant.  In  any  case  a  considerable  amount 
always  distils  off  during  concentration,  and  hence  all  fume 
lines  and  scrubbers  must  be  run  hot  to  prevent  stoppages. 
To  reduce  troubles  of  this  nature  to  a  minimum  denitration 
is  sometimes  carried  out  with  highly  superheated  steam, 
about  500°  C.,  and  this  is  undoubtedly  the  best  way,  as  the 
high  temperature  rids  the  acid  more  or  less  of  its  volatile 
constituents  and  not  only  saves  trouble  in  the  concen- 
trating plant,  but  also  makes  concentration  more  easy  by 
reducing  the  amount  of  organic  matter. 

Owing  to  the  stable  nature  of  the  organic  matter  in  the 
sulphuric  acid,  concentration  requires  a  far  higher  tempera- 
ture than  is  the  case  with  the  acids  from  nitroglycerine  and 
nitrocellulose.  For  this  reason  the  cascade  type  of  plant  is 
almost  invariably  employed,  and  it  is  usually  finished  up  with 
a  cast-iron  pan  or  pans.  These  can  be  fired  from  the  same 
furnace  as  the  rest  of  the  cascade,  but  are  much  better  fired 
separately.  The  "  fume  "  from  these  pans  is  at  a  high  tempe- 
rature and  is  sometimes  used  for  denitrating  the  feed  acid. 

If  the  denitration  has  been  carried  out  at  a  high  tempera- 
ture so  that  the  denitrated  acid  is  comparatively  poor  in 
organic  matter,  concentration  can  be  carried  out  in  the 
Kessler  plant,  but  the  heavy  sludge  is  very  apt  to  settle 
out  in  the  plateaux  and  block  up  the  culottes,  so  that 
T-  5 


66  EXPLOSIVES 

the  modified  Kessler  plants  (such  as  the  A.G.D.  Concentrator) 
would  probably  give  better  results. 

This  sludge  is  chiefly  sulphate  of  iron  which  has  been 
picked  up  from  the  iron  nitrators  or  from  the  waste  acid  store 
tanks  when  these  are  made  of  steel.  It  is  extremely  trouble- 
some, as  it  settles  out  in  various  parts  of  the  plant  and  causes 
stoppages,  and  settles  out  in  the  basins  of  the  cascade  and 
causes  them  to  crack.  It  cannot  be  avoided,  but  can-  be 
reduced  somewhat  by  using  lead  in  preference  to  iron, 
especially  when  handling  waste  acid.  Certainly  this  results 
in  the  formation  of  lead  sulphate,  but  the  amount  is  much 
less  and  it  is  somewhat  less  troublesome  to  deal  with. 

LITERATURE 

NITROGLYCERINE 

A  description  of  some  of  the  older  methods  of  manufacture  will  be 
found  in  "  Manufacture  of  Explosives,"  O.  Guttmann,  London,  1905. 
An  account  of  the  modern  displacement  process  will  be  found  in  A.E., 
1906,  p.  90  ;  J. S.C.I.,  1908,  193. 

Accidents  in  the  manufacture  of  nitroglycerine  have  been  numerous, 
and  the  following  Special  Reports  are  very  instructive  :  S.R.,  150, 156, 161. 
162,  164,  167,  180,  200. 

NITROCELLULOSE 

A  great  deal  of  information  on  nitrocellulose  for  both  explosive  and 
other  purposes  will  be  found  in  "  The  Nitrocellulose  Industry,"  by  E.  C. 
Worden,  2  vols.,  London,  1911. 

The  displacement  process  is  described  in  detail  in  A.E.,  1906,  p.  77, 
whereas  nitrating  centrifuges  are  described  and  fully  illustrated  in  5.5., 
1910,  pp.  352,  413,  434,  458,  478. 

The  Abel  process  is  described  in  detail  in  the  Journal  of  the  Society  of 
Chemical  Industry,  1909, 180.  The  following  Special  Reports  on  accidents 
will  repay  study  :  S.R.,  166,  169,  206,  207. 

TRINITROTOLUOL 

The  following  references  deal  with  its  stability,  use  as  an  explosive,  and 
toxic  properties  :  A.E.,  1914,  68  ;  5.5.,  1912,  425  ;  1913,  97,  213  ;  1914, 
239,  378»  4°5,  432  ;  P.S.,  xvi.,  40,  97,  213. 

The  majority  of  accidents  that  have  been  due  to  T.N.T.  have  taken 
place  during  the  war  and  reports  are  not  yet  available.  The  following, 
however,  will  be  found  of  interest :  5.5.,  1907,  333,  413,  416  ;  1908,  298  ; 
1909,  213;  A.R.,  1903,26. 

PICRIC  ACID 

The  best  description  of  the  manufacture  of  picric  acid  will  be  found  in 
Metallurgical  and  Chemical  Engineering,  1915,  p.  686. 
For  accidents,  see  S.R.,  81,  139. 

TETRANITROANILINE  AND  TETRYL 

A.E.,  21,  21.  36;  24,  137,  144;  25,  38. 
5.5.,  1913,  185. 


SECTION  III.— SMOKELESS  PROPELLANTS 

PROPEU.ANTS  FOR  RIFLED  ARMS. 

THE  properties  of  a  propellant  for  use  with  rifled  arms  are 
somewhat  different  from  those  required  by  smooth-bore 
arms,  as  the  former  require  a  slow-burning  powder  that 
will  impart  a  "push  "  to  the  projectile,  whereas  shot  guns 
call  for  a  more  rapidly  burning  explosive,  the  effect  of  which 
is  more  akin  to  a  blow.  The  projectile  in  a  rifled  arm 
engages  closely  with  the  rifling,  copper  bands  ("  gas  checks  " 
or  "  driving  bands  ")  being  provided  for  this  purpose  in 
the  case  of  steel  shell,  so  that  comparatively  little  gas  can 
escape  before  the  projectile  leaves  the  muzzle.  If  a  rapidly 
burning  powder  is  used  combustion  will  be  complete  before 
the  projectile  has  travelled  any  appreciable  distance,  and 
excessive  and  dangerous  pressure  will  be  developed.  This 
pressure,  moreover,  will  fall  off  rapidly,  so  that  in  addition 
only  low  muzzle  velocity  will  be  attained.  If  on  the  other 
hand  a  suitable  slow -burning  powder  is  employed  combustion 
will  take  place  during  the  whole  travel  of  the  projectile,  so 
that  a  steady  pressure  will  be  maintained  and  high  muzzle 
velocity  without  excessive  pressure  will  be  achieved.  To 
maintain  an  even  pressure  until  the  moment  that  the  pro- 
jectile leaves  the  muzzle  is  usually  mechanically  impossible, 
as  it  is  impossible  to  construct  most  guns  with  the  same 
thickness  of  metal  at  the  muzzle  as  at  the  breach,  but  the 
longer  the  gun  the  slower  burning  must  be  the  propellant. 
In  rifled  arms  the  maximum  pressure  developed  is  usually 
about  15  tons  per  square  inch,  whereas  in  shot  guns  it  is 
only  about  2-4  tons. 

Before  the  introduction  of  smokeless  powder,  slowness 
01  burning  was  attained  by  the  use  of   moulded  powders, 


68  EXPLOSIVES 

some  of  the  pellets  being  as  much  as  ij  in.  long.  The  re- 
duction of  surface  achieved  by  moulding  the  powders  caused 
them  to  burn  much  more  slowly,  as  combustion  takes  place 
only  on  the  surface.  Naturally  as  the  powder  burns  the 
pellets  become  smaller,  and  consequently  the  surface  less. 
In  order  to  compensate  for  this  and  maintain  a  steady  rate 
of  combustion,  they  were  made  with  one  or  more  perfora- 
tions. With  these  powders,  although  the  external  surface 
decreased  during  combustion,  the  internal  surface  increased, 
so  that  by  choosing  a  suitable  number  of  perforations  a  very 
steady  rate  of  combustion  could  be  and  was  obtained. 
These  moulded  powders  have  now  gone  quite  out  of  use, 
but  the  same  principle  is  applied  to  smokeless  powders,  viz. 
the  rate  of  combustion  is  controlled  by  the  size  of  the  powder. 
The  following  qualities  are  required  of  an  ideal  smokeless 
powder : — 

(i)  Regular  Ballistics. — Regular  ballistics  are  only 
attained  with  a  regular  rate  of  burning.  For  this  reason 
the  powder  must  not  be  so  brittle  that  it  breaks  up  during 
transport  or  combustion,  and  it  must  not  be  porous  so  that 
combustion  can  spread  through  the  mass  without  being 
confined  to  the  surface.  With  tubular  or  perforated  powders 
mechanical  strength  is  necessary,  as  the  gas  pressure  inside 
the  tubes  is  greater  than  that  outside,  and  consequently 
if  the  material  is  mechanically  weak  the  tubes  will  burst. 
The  effective  surface  of  flake  powders  may  become  reduced 
owing  to  the  flakes  lying  face  to  face,  and  with  a  view  to 
preventing  this  some  flake  powders  are  made  with  ridges 
or  knobs.  Finally,  the  powder  must  contain  little  or  no 
volatile  matter  that  can  evaporate  during  storage  and 
thereby  alter  the  composition  of  the  explosive,  and  it  should 
not  be  affected  by  climatic  conditions,  e.g.  must  not  be 
subject  .to  freezing. 

(2)  Stability. — This  is  very  necessary  in  the  case  of 
military  powders  which  may  be  kept  in  storage  for  many 
years  before  use.  The  most  stable  powders  are  usually 
those  which  are  least  porus,  as  porosity  frequently  leads  to 
instability  through  oxidation.  They  are  also  less  hygroscopic. 


SMOKELESS  PROPELLANTS  69 

(3)  Absence  of  Fouling. — The  powder  must  produce  a 
minimum  of  fouling,  and  this  should  be  of  such  a  nature 
that  it  is  easily  removed.    The  products  of  combustion 
should  contain  no  substance  capable  of  corroding  the  barrel. 

(4)  Absence  of  Smoke. — This  can  only  be  achieved  by 
powders  which  on  combustion  give  only  products  which 
are   gaseous   at   the   ordinary   temperature.     All  powders 
produce  water  on  combustion,  and  in  very  cold  weather 
this  is  sometimes  condensed  to  a  mist.     Any  powder  con- 
taining a  nitrate  produces  more  or  less  smoke  owing  to 
solid  matter,  as  ammonium  nitrate  is  the  only  nitrate  giving 
gaseous  decomposition  products,  and  this  cannot  be  used 
owing  to  its  deliquescent  nature. 

(5)  Absence    of   Fume. — The    products    of    combustion 
should  not  contain  any  poisonous  gas.     Carbon  monoxide 
is  almost  always  present,  but  is  not  dangerous  under  the 
conditions  under  which  propellants  are  used.    The  muzzle 
gases    of   propellants    containing    nitroglycerine,    however, 
frequently  contain  a  certain  amount  of  this  compound,  and 
in    consequence   give   rise   to    "  gun   headache."    This   is 
particularly  the  case  with  heavy  ordnance. 

(6)  Absence  of  Erosion. — Erosion  is  due  to  two  causes, 
viz.  the  scouring  action  of  solid  particles  and  the  tempera- 
ture attained  by   the  interior  surface  of  the  arm.    The 
erosion  caused  by  black  powder  is  due  almost  solely  to  the 
scouring  effect  of  the  solid  products  of  combustion,  whereas 
in  the  case  of  modern  smokeless  powders  erosion  is  due 
to  the  surface  of  the  metal  being  fused  and  then  washed 
away  by  the  outrush  of  the  gases,  and  consequently  to 
avoid  erosion  the  temperature  of  combustion  must  be  kept 
down. 

(7)  Absence  of  Back-flash.— Back-flash    is  due    to  the 
products  of  combustion  being  rich  in  carbon  monoxide  and 
this  firing  when   the  breach   is   opened.     It  is   especially 
dangerous  in  artillery,  and  many  accidents  have  been  caused 
by  its  firing  other  charges  lying  in  the  turret.    It  can  only 
be  avoided  by  using  a  powder  containing  sufficient  oxygen 
to  burn  all  the  carbon  to  carbon  dioxide. 


70  EXPLOSIVES 

(8)  Absence  of  Flash. — Flash  is  objected  to  in  military 
explosives,  as  it  reveals  the  position  of  the  gun  when  night 
firing  is  taking  place.     It  can  be  remedied  by  the  addition 
of  neutral  salts,  but  these  produce  smoke  which  is  obj  ection- 
able  by  day. 

(9)  High  Power  and  Density. — The  greater  the  power  of 
an  explosive,  the  less  is  the  weight  required  to  produce  a 
given  effect.     This  is  important  from  a  military  point  of 
view,  as  it  saves  transport  and  means  less  weight  for  the 
soldier  to  carry.     A  high  density  means  that  less  room  is 
required  for  storage,  and  is  specially  desirable  for  naval 
purposes  where  magazine  accommodation  is  limited. 

(10)  Insensitiveness  to  Shock. — This  is  also  more  important 
for  military  than  for  sporting  purposes.    For  use  under 
service  conditions  a  high  degree  of  insensitiveness  is  very 
desirable,  as  the  explosive  should  not  explode  when  struck, 
for  example,  by  a  rifle  bullet. 

(n)  Quickness. — The  powder  should  not  show  any 
tendency  to  hang  fire  when  fired  with  a  suitable  cap  and 
primer. 

Smokeless  propellants  for  rifled  arms  can  be  divided 
into  two  classes,  viz.  those  consisting  of  nitroglycerine  and 
nitrocellulose  with  or  without  the  addition  of  small  quantities 
of  other  materials  to  act  as  stabilizers  or  deterrents,  and 
nitrocellulose  powders,  containing  no  nitroglycerine,  but 
consisting  of  nitrocellulose  with  or  without  the  addition 
of  stabilizers,  deterrents,  or  nitrates.  Although  both 
classes  contain  nitrocellulose,  the  latter  are  known  as  nitro- 
cellulose powders  and  the  former  as  nitroglycerine  powders. 
The  stabilizers  are  compounds  which  are  capable  of  taking 
up  the  products  of  decomposition  and  thus  maintaining 
the  powder  in  a  state  of  neutrality  and  preventing  auto- 
catalysis.  For  this  purpose  magnesium  carbonate  or  chalk 
is  sometimes  used,  especially  for  stabilizing  nitrocellulose, 
the  latter  usually  being  applied  by  using  hard  water 
during  the  boiling  process  (p.  50).  Of  organic  compounds, 
camphor  was  used  at  one  time,  but  it  is  objectionable,  as  it 
is  volatile,  and  hence  powders  made  with  camphor  are  liable 


SMOKELESS  PROPELLANTS  71 

to  give  irregular  ballistics  after  keeping.  It  is  now  almost 
wholly  replaced  by  diphenylamine  or  mineral  jelly  (crude 
vaseline)  although  other  substances  have  been  proposed, 
such  as  diphenylurea,  urea,  etc. 

Both  nitroglycerine  and  nitrocellulose  powders  consist  of 
colloidal  masses  of  gelatinized  nitrocellulose  which  have  been 
pressed  into  ribbons,  cords,  tubes  or  sheet,  these  being  fre- 
quently subsequently  cut  into  flakes  when  intended  for  use 
with  small  arms.  A  very  lively  controversy  has  arisen  as  to 
the  relative  merits  of  the  two  classes  of  powders,  and  the 
question  cannot  be  said  to  be  settled.  Against  nitroglycerine 
propellants  it  has  been  urged  that  the  fumes  of  unburnt 
nitroglycerine  cause  severe  headache,  especially  in  the  case 
of  heavy  ordnance,  that  they  are  liable  to  freeze  at  low  tem- 
peratures and  that  the  high  temperature  of  explosion  causes 
excessive  erosion  of  the  gun  barrel.  In  connection  with  this 
latter  point  Vicille  carried  out  quantitative  experiments  by 
firing  charges  in  a  closed  cylinder  from  which  the  only  escape 
for  the  gases  was  through  a  hole  i  mm.  in  diameter  in  a 
movable  plug.  The  plug  was  weighed  before  and  after 
each  shot,  and  the  loss  in  weight  taken  as  a  measure  of  the 
erosion.  He  found  that  Cordite  had  a  much  greater  erosive 
effect  than  Poudre  B  (a  nitrocellulose  propellant),  and 
experiments  carried  out  by  Sir  Alfred  Nobel  with  special 
Cordites  containing  from  10  to  60  per  cent,  of  nitro- 
glycerine showed  that  within  these  limits  the  erosion  in- 
creased by  some  600  per  cent.  On  the  other  hand,  it  has 
been  stated  that  the  erosion  caused  by  Cordite  M.D.,  which 
contains  much  less  nitroglycerine  than  Cordite  Mark  I.,  is 
only  slightly,  if  any,  greater  than  that  caused  by  the  average 
nitrocellulose  powder. 

In  favour  of  nitroglycerine  powders,  it  has  been  urged 
that  they  are  cheaper  to  make,  give  more  regular  ballistics, 
and  are  less  liable  to  produce  back-flash  than  nitrocellulose 
powders.  They  keep  very  well,  are  not  liable  to  become 
porous,  and  the  solvent  can  be  almost  completely  expelled, 
whereas  nitrocellulose  powders  are  liable  to  become  degela- 
tinized  and  porous,  and  it  is  almost  impossible  to  expel  the 


72  EXPLOSIVES 

solvent  by  drying  for  any  reasonable  time,  and  hence  it  is 
usually  necessary  to  leave  from  2-4  per  cent,  in  the  explosive. 
This  gradually  evaporates  on  keeping,  and  its  loss  naturally 
alters  the  ballistics.  Nitroglycerine  propellants  are  also 
more  powerful  and  dense  than  nitrocellulose  powders,  so 
that  somewhat  less  transport  and  storage  space  are  required 
for  them,  great  advantages  from  a  military  point  of  view. 

It  is  notable  that  Great  Britain  and  Italy  are  the  only 
two  first-class  Powers  that  rely  on  nitroglycerine  powders 
for  all  classes  of  arms  both  military  and  naval.  The  other 
Powers  either  use  nitrocellulose  powders  exclusively,  e.g. 
France,  Russia,  and  the  United  States,  or  use  nitrocellulose 
propellants  for  some  arms  and  nitroglycerine  propellants  for 
others,  e.g.  Germany.  As  the  best  test  of  a  propellant  is 
its  prolonged  trial  under  use,  the  war  should  furnish  interesting 
data  as  to  the  relative  merits  of  the  two  classes  of  powders. 


NITROGLYCERINE 

The  first  propellant  of  this  class  was  discovered  by  Nobel 
in  1887  and  named  Ballistite.  It  was  manufactured 
originally  by  incorporating  collodion  cotton  with  nitro- 
glycerine in  the  presence  of  benzole,  but  the  method  was 
soon  changed,  as  it  was  found  that  incorporation  could  be 
carried  out  by  agitating  nitroglycerine  with  collodion 
cotton  in  the  presence  of  hot  water,  agitation  being  effected 
by  means  of  compressed  air.  The  dough  thus  formed  is 
then  rolled  between  rollers  heated  at  5o°-6o°  C.  until  a 
completely  homogeneous  and  colloidal  sheet  is  obtained, 
which  is  finally  cut  into  flakes  and  usually  coated  with 
graphite.  The  Ballistite  thus  obtained  contains  on  the 
average  equal  weights  of  nitroglycerine  and  nitrocellulose, 
and  usually  a  few  tenths  of  a  per  cent,  of  diphenylamine 
to  act  as  a  stabilizer.  Owing  to  the  high  temperature  of 
explosion  Ballistite  causes  severe  erosion,  and  has  now  been 
largely  displaced  by  Cordite  and  similar  explosives  containing 
less  nitroglycerine. 

Cordite. — Cordite  was  introduced  as  the  British  Service 


SMOKELESS  PROPELLANTS  73 

propellant  in  1889,  and  originally  consisted  of  nitroglycerine, 
guncotton,  and  mineral  jelly  (crude  vaseline)  in  the  following 
proportions  : — 

Nitroglycerine  . .          . .         . .  58 

Guncotton        . .          . .          . .          . .     37 

Mineral  jelly     . .          . .          . .          . .       5 

In  spite  of  the  cooling  action  of  the  mineral  jelly,  however, 
the  erosion  caused  to  the  guns  was  so  severe  that  the  com- 
position had  to  be  modified.  The  Cordite  in  use  at  present 
has  the  composition — 

Nitroglycerine  . .         . .         . .         . .     30 

Guncotton        65 

Mineral  jelly     . .          . .          . .          . .       5 

and  is  known  as  Cordite  M.D.  to  distinguish  it  from  the 
original  Cordite  (Cordite  Mark  I.),  which  is  still  used  for 
some  purposes. 

The  guncotton  used  in  the  manufacture  of  Cordite  is 
usually  manufactured  from  cotton  waste  by  the  displace- 
ment process  and  contains  13  per  cent,  of  nitrogen,  and  85 
per  cent,  is  insoluble  in  alcohol-ether.  The  mineral  jelly 
must  not  flash  below  400°  Fahr.  (204*5°  C.)  and  must  not 
melt  completely  below  30°  C.  It  must  be  free  from  acidity 
and  mineral  impurities  and  its  specific  gravity  at  38°  C. 
should  not  be  less  than  -87. 

The  manufacture  of  Cordite  is  carried  out  in  this  country 
as  follows,  other  nitroglycerine  propellants  being  made  by 
very  similar  methods.  The  guncotton,  after  drying  and 
subsequent  cooling,  is  weighed  out  in  the  stoves  into  india- 
rubber  bags  holding  about  25  Ibs.  each,  lead  weights  covered 
with  leather  or  rubber  being  used.  These  bags  are  then 
carried  to  the  nitroglycerine  department,  and  the  required 
weight  of  nitroglycerine  measured  off  and  poured  into  each 
bag.  The  nitroglycerine  can  be  measured  out  either  in 
fixed  lead  measuring  vessels  or  in  movable  gutta-percha 
jugs.  The  bags  are  then  taken  to  the  hand-mixing  house, 
where  the  contents  are  emptied  out  and  mixed  by  hand, 
being  finally  rubbed  gently  through  a  J-in.  mesh  sieve  into 
other  bags.  These  "hand  mixings"  are  much  safer  than 


74  EXPLOSIVES 

nitroglycerine  or  guncotton  alone,  and  most  factories  keep 
a  small  stock  of  cordite  paste  in  this  form  so  as  to  facilitate 
regular  work.  The  next  process  consists  in  incorporating 
the  paste  with  a  mutual  solvent  so  as  to  gelatinize  the  nitro- 
cellulose. Acetone  has  been  found  most  suitable  for  this 
purpose  and  is  always  used,  although  at  an  emergency  ether- 
alcohol  could  be  substituted,  and  this  has  been  done  to  a 
considerable  extent  during  the  war.  The  incorporation  is 
carried  out  in  kneading  machines  of  the  Werner-Pfleiderer 
type  (Fig.  15)  and  takes  seven  hours.  The  average  charge 
per  machine  is  150-250  Ibs.,  and  before  adding  the  paste 
the  interior  of  the  machine  is  moistened  with  acetone.  The 
paste  and  the  rest  of  the  acetone  is  then  added  and  the 
machine  set  in  motion,  the  mineral  jelly  being  added  when 
the  incorporation  is  half  finished,  viz.  at  the  end  of  3!  hours. 
The  stiff  dough  heats  up  somewhat  during  mixing,  but  the 
temperature  is  not  allowed  to  exceed  40°  C.  and  is  controlled 
by  the  water  jacket  with  which  the  mixer  is  provided. 
To  prevent  undue  loss  of  acetone  a  light  wooden  cover  is 
placed  over  the  machine.  The  belts  of  the  machines  are 
liable  to  become  strongly  electrified,  and  ensuing  sparks 
may  cause  an  acetone  vapour  explosion.  To  remedy  this 
the  machines  are  earthed  and  the  belts  dressed  with  a  mixture 
of  glycerine  and  water. 

When  incorporation  is  complete  the  charge  is  placed  in 
bags  and  removed  to  the  press  house,  where  it  is  filled  into 
gun- metal  cylinders,  usually  being  packed  tight  by  a 
hydraulic  ram,  and  then  pressed  through  a  die  in  a  hydraulic 
press  into  cords  (hence  the  name  "  Cordite  ")  of  various 
sizes  or  into  tubes,  a  loo-mesh  gun-metal  gauze  being  placed 
above  the  die  to  filter  out  foreign  matter.  Pressing  into 
tubes  is  effected  by  means  of  a  die  with  a  pin  in  the  centre, 
but  when  small  sizes  are  being  pressed  considerable  trouble 
is  experienced  through  a  partial  vacuum  being  formed  and 
consequent  collapse  of  the  tube.  This  can  be  avoided  by 
using  a  hollow  pin  with  communication  to  the  outer  air 
(B.P.  27,700!°). 

The  diameter  of  the  cord  depends  on  the  size  of  the 


& 

H 


76  EXPLOSIVES 

gun  for  which  the  Cordite  is  wanted.  The  largest  size 
pressed  is  approximately  -5  of  an  inch  in  diameter,  but  all 
Cordite  is  pressed  through  a  die  two  or  three  hundredths  of 
an  inch  larger  than  the  desired  diameter  of  the  finished 
article  so  as  to  allow  for  shrinkage  during  drying.  The 
smaller  sizes  of  Cordite  are  reeled  on  to  drums  as  the  cords 
issue  from  the  press,  but  the  larger  sizes  are  laid  out  on  a 
table  and  then  cut  to  the  required  length.  Drying  is  effected 
in  stoves  heated  to  40°  C.  and  takes  from  a  few  days  to 
two  or  three  months,  the  time  depending  on  the  diameter 
of  the  cords,  but  Cordite  Mark  I.  dries  considerably 
quicker  than  Cordite  M.D. 

After  drying  is  complete,  different  batches  of  Cordite 
are  blended  in  order  to  assure  a  product  with  regular  ballistic 
properties.  With  the  smaller  sizes  which  are  on  reels,  such 
as  rifle  Cordite,  this  is  very  simply  done  by  re-winding 
several  reels  simultaneously  on  to  a  single  drum.  The 
worker  carrying  out  this  process  should  be  carefully  earthed, 
as  the  dry  Cordite  passing  through  his  hands  becomes 
strongly  electrified.  The  bigger  sizes  are  blended  by  laying 
the  boxes  containing  the  different  batches  in  a  row  and  then 
repacking  by  transferring  a  handful  from  each  into  a  different 
box.  The  weight  per  linear  inch  is  usually  relied  on  as  a 
guide  for  making  up  blends.  Before  blending  the  sticks 
are  carefully  picked  over  by  hand,  and  any  which  are  badly 
distorted  or  contain  specks  of  foreign  matter  thrown  out. 
These  specks  are  chiefly  due  to  brass  dust  formed  by  sliding 
the  cylinders  over  brass  guides  in  the  press  house,  and  are 
difficult  to  avoid.  Such  sticks  as  are  rejected  in  the  packing 
house  are  re-worked  after  being  incorporated  again  with 
acetone. 

The  various  sizes  of  Cordite  used  by  the  British  Government 
are  denoted  by  a  fraction,  the  numerator  of  which  denotes 
the  diameter  in  hundredths  of  an  inch  and  the  denominator 
the  length  of  the  sticks  in  inches.  For  example,  size  f  f 
means  that  the  sticks  are  '45  in.  in  diameter  and  25  in.  long. 

Cordite  forms  a  horny  mass  of  brownish-yellow  colour. 
The  smaller  sizes  are  flexible,  but  the  larger  sizes  break 


SMOKELESS  PROPELLANTS  77 

easily  if  bent.  Cordite  Mark  I.  is  much  more  flexible  than 
Cordite  M.D.  It  is  very  insensitive  to  shock,  and  when 
not  strongly  confined  burns  fiercely,  but  does  not  explode. 
The  cost  of  manufacturing  Cordite  during  the  period  January 
— June,  1918,  was  about  £225  per  short  (?)  ton  (C.T.J.,  1919, 
p.  189). 

In  the  manufacture  of  Cordite  56  Ibs.  of  acetone  are 
required  for  every  100  Ibs.  of  guncotton,  and  for  the  sake  of 
economy  it  is  necessary  to  recover  this  as  far  as  possible, 
by  suitably  treating  the  air  exhausted  from  the  drying 
stoves.  According  to  one  process  the  acetone-laden  air 
is  forced  through  water  contained  in  a  series  of  closed 
jars  arranged  in  the  form  of  a  cascade,  the  water  and  air 
flowing  in  contrary  directions.  By  this  means  the  air 
is  robbed  of  its  acetone,  and  this  latter  can  be  recovered 
by  distilling  the  water  with  a  suitable  column.  The 
process  in  most  general  use,  however,  takes  advantage 
of  the  fact  that  acetone  forms  an  addition  compound  with 

QTT 

sodium  bisulphite,  the  formula  of  which  is  (CH3)2C<qQ -j^.  . 

The  recovery  by  this  process  is  carried  out  by  passing  the 
air  from  the  stoves  up  lead-lined  towers  which  are  packed 
with  frames  on  which  strands  of  wool  are  woven  in  a  criss- 
cross pattern  (B.P.  25,99401).  Simultaneously  a  strong 
solution  of  sodium  bisulphite  is  allowed  to  trickle  down  the 
towers,  the  towers  being  usually  connected  in  series,  and 
the  liquor  from  the  bottom  of  one  pumped  to  the  top  of  the 
next.  By  this  means  the  liquor  and  air  are  brought  into 
contact  with  one  another  on  the  counter-current  system 
and  very  complete  scrubbing  is  effected.  After  circulating 
through  the  towers  the  liquor  is  distilled,  a  little  sodium 
carbonate  being  first  added,  and  the  acetone  thus  recovered 
purified  by  fractionation. 

In  all  recovery  processes  there  are  two  dangers  to  be 
guarded  against.  One  is  that  fire  from  one  stove  may  be 
transmitted  to  other  stoves  through  the  pipe  line  connecting 
them  with  the  recovery  plant.  This  can  be  guarded  against 
by  inserting  fine  wire  gauzes  in  the  pipes,  these  acting  on 


78 


EXPLOSIVES 


the  same  principle  as  the  Davy  safety  lamp.  It  is  also 
advisable  to  make  some  sections  of  the  pipe  of  very  flimsy 
construction,  so  that  they  would  be  broken  by  an  explosion 
wave.  The  second  danger  is  that  Cordite  gives  off  consider- 
able quantities  of  nitroglycerine  during  drying,  especially 
during  the  later  stages,  and  this  is  apt  to  condense  and 
accumulate  in  the  pipes.  To  avoid  this,  all  pipe  lines  must 
be  constructed  with  a  fall  to  one  or  more  points  at  each  of 
which  a  catch  box  is  placed  from  which  any  accumulation 
of  nitroglycerine  can  be  drawn  off  safely  and  conveniently. 
Some  firms  make  a  point  of  keeping  a  little  paraffin  oil  of 
medium  consistency  (such  as  medium  machinery  oil)  in 
these  catch  boxes,  as  this  has  a  great  effect  in  moderating 
the  explosive  properties  of  nitroglycerine. 

The  amount  of  solvent  given  off  during  the  later  stages 
of  drying  large  size  Cordite,  especially  Cordite  M.D.,  is  so 
small  that  it  does  not  pay  to  recover  it.  Hence  it  is  usual 
to  transfer  these  larger  sizes  to  non-recovery  stoves  after 
they  have  lost  the  greater  part  of  their  solvent. 

The  following  gives  the  name,  composition,  and  physical 
form  of  the  nitroglycerine  propellants  used  for  military 
purposes  by  European  Powers.  The  other  Powers  use 
nitrocellulose  propellants : — 


Country. 

Propellant. 

N.G. 

N.C. 

MJ. 

Form. 

Remarks. 

Gt.  Britain 

Cordite  Mark  I. 
„       M.D.  II. 

58 
30 

37 
65 

5 
5 

{Sticks  } 
(Tubes  ) 

N.C.  has  13  %  N. 

Italy 

Filite 

50 

50 

— 

Cords 

i  %  Ph2NH. 

Solenite 

64 

3 

N.C.  12-5  %N. 

Germany 

Wiirfelpulver 
Rohrenpulver 

33 

50 

64 

3 

Cubes 
Tubes 

Contains  Ph2NH. 

Cordite  is  very  largely  used  for  sporting  rifles,  and  in 
addition  one  or  two  nitroglycerine  propellants  are  manu- 
factured in  this  country  for  sporting  purposes.  Of  these 
Axite  and  Moddite  are  the  best  known.  The  former  is 
practically  Cordite  M.D.  to  which  2,  per  cent,  of  potassium 
nitrate  has  been  added.  The  latter  contains  rather  more 


SMOKELESS  PROPELLANTS  79 

nitroglycerine,  and  Marshall  ("  Explosives  ")  gives  the  result 
of  an  analysis  as  follows  : — 

Nitroglycerine  . .          . .         . .  38*7 

Nitrocellulose 56-8 

Mineral  jelly  . .          . .          . .  4-3 

Volatile      . .  . .          . .          . .  -2 

NITROCELLULOSE  PROPELLANTS 

These  all  consist  of  collodion  cotton  gelatinized  and 
rendered  colloidal  by  the  use  of  solvents  and  then  pressed 
into  cords,  tubes,  or  ribbons  in  much  the  same  way  as  Cordite. 
Gelatinization  can  be  carried  out  with  acetone,  but  the 
colloid  thus  obtained  is  very  brittle  and  becomes  more  so 
on  keeping,  so  that  ether- alcohol  is  nearly  always  used.  As 
this  does  not  gelatinize  nitrocellulose  of  high  nitrogen 
content,  it  is  very  desirable  to  use  a  collodion  cotton  which 
is  almost  completely  soluble  in  ether-alcohol,  as  otherwise 
ungelatinized  fibres  will  render  the  resulting  colloid  porous. 
Porosity  is  usually  accompanied  by  instability  as  oxidation 
takes  place,  and  by  irregular  ballistics  and  excessive  pressures 
due  to  combustion  spreading  through  the  body  of  the 
powder  and  not  remaining  confined  to  the  surface. 

Nitrocellulose  propellants  for  rifled  arms  usually  contain 
nothing  but  nitrocellulose,  together  with  a  small  amount  of 
stabilizers  and  a  slight  percentage  of  solvent  which  cannot 
be  removed  in  any  reasonable  time  in  the  drying  stoves. 
More  rarely  they  contain  a  little  potassium  nitrate,  but 
propellants  containing  nitrates  are  more  used  for  shot  guns 
than  for  rifled  arms,  and  as  they  are  manufactured  by 
somewhat  different  methods  they  will  be  treated  separately. 
As  gelatinization  is  almost  invariably  brought  about  by 
alcohol-ether,  the  somewhat  dangerous  process  of  drying 
the  nitrocellulose  can  be  avoided,  the  water  being  displaced 
by  alcohol  as  described  on  page  52. 

Almost  all  countries  have  adopted  nitrocellulose  pro- 
pellants for  military  purposes,  and  the  manufacture  of  the 
United  States  Military  Powder  serves  as  a  general  descrip- 
tion of  the  methods  employed. 


8o  EXPLOSIVES 

U.S.  Military  Powder. — The  nitrocellulose  is  prepared 
from  cotton  waste  either  by  the  displacement  process  or 
in  nitration  centrifuges,  and  contains  127  per  cent,  of  nitrogen. 
It  is  almost  completely  soluble  in  alcohol-ether,  and  is 
pulped,  washed,  and  whizzed  in  the  ordinary  way.  Forty 
pounds  of  the  wet  pulp,  which  contains  30  per  cent,  of 
water,  are  then  packed  into  a  cylinder  and  treated  with 
alcohol.  At  first  no  pressure  is  applied  and  the  runnings 
are  almost  pure  water,  but  after  rather  more  than  half  a 
gallon  of  water  has  run  out  pressure  at  200  Ibs.  per  square 
inch,  and  finally  at  3500  Ibs.  per  square  inch,  is  applied.  The 
block  or  "  cheese "  thus  obtained  weighs  some  38  Ibs. 
and  contains — 

Nitrocellulose       . .          . .  73  per  cent. 

Alcohol     . .          . .          . .          . .     23 

Water 4 

The  blocks  are  roughly  broken  up  by  wooden  mallets  and 
the  disintegration  completed  by  running  them  in  a  Werner 
and  Pfleiderer  mixing  machine  (Fig.  15,  p.  75)  for  a  quarter 
of  an  hour.  Bach  machine  takes  a  charge  of  three  blocks, 
corresponding  to  42  Ibs.  of  pure  nitrocellulose.  After 
disintegration  is  complete  48$  Ibs.  of  ether,  in  which  6  oz. 
of  diphenylamine  has  been  dissolved,  are  added  to  each 
machine  and  incorporation  carried  on  for  45  minutes.  The 
charge  is  then  transferred  to  hydraulic  presses  and  sub- 
mitted to  a  presstire  of  3500  Ibs.  per  square  inch,  whereby 
it  is  converted  into  elastic  horny  blocks  weighing  about 
40  Ibs.  each,  but  no  solvent  is  squeezed  out  during  the  com- 
pression. To  get  rid  of  foreign  matter,  such  as  wood  chips 
and  hard  nodules,  the  colloid  is  next  filtered  through  a 
3O-mesh  gauze  resting  on  a  heavy  steel  plate  perforated 
with  ^-in.  holes.  Filtration  is  brought  about  by  applying 
a  pressure  of  3500  Ibs.  per  square  inch,  and  the  powder  issues 
in  the  form  of  cords.  These  are  again  pressed  into  a  block 
at  3500  Ibs.  per  square  inch  and  this  block  then  squirted 
into  multitubular  cords  in  a  hydraulic  press,  the  cords 
having  different  diameters  and  a  different  number  of  perfora- 
tions (from  i  to  7),  according  to  the  purpose  for  which  the 


SMOKELESS  PROPELLANTS  81 

powder  is  required.  These  multitubular  cords  are  immedi- 
ately cut  up  into  short  lengths  by  means  of  revolving  knives 
and  dried  in  stoves. 

During  the  squirting  of  the  cords  a  great  deal  of  heat  is 
evolved,  so  that  water-cooled  dies  must  be  used.  It  is  not 
advisable,  however,  to  carry  this  cooling  too  far,  as  the 
cutting  knives  work  best  at  30°  C. 

After  squirting  and  cutting  the  powder  contains  about 
48  per  cent,  of  solvent,  rather  more  than  half  of  which  is 
ether.  Owing  to  its  volatility  and  to  the  fact  that  it  does 
not  form  addition  compounds  easily,  ether  is  much  more 
difficult  to  recover  than  acetone,  and  not  more  than  40  per 
cent,  can  be  recovered  economically,  and  this  only  by 
using  condensers  served  with  chilled  brine.  The  tempera- 
ture of  the  condensers,  however,  must  not  be  reduced  too 
far,  or  the  water  vapour  which  comes  over  simultaneously 
may  be  frozen  and  so  cause  a  stoppage.  The  ether  recovered 
is  mixed  with  a  good  deal  of  alcohol,  and  is  best  returned 
to  the  ether  factory.  The  finished  powder  contains  from 
3  to  7  per  cent,  of  solvent,  depending  on  the  size. 

Poudre  B. — This  is  the  French  military  powder,  and  is 
made  from  a  mixture  of  soluble  and  insoluble  nitrocellulose 
gelatinized  with  ether-alcohol  to  which  some  diphenylamine 
and  amyl  alcohol  have  been  added.  The  latter  is  used  as 
it  is  left  in  the  finished  explosive,  and  is  less  volatile  than 
alcohol  or  ether.  After  incorporation  the  mass  is  worked 
between  rollers  at  70°  C.,  and  the  rolled  sheets  either  cut  up 
in  strips  or  flakes  or  squirted  through  a  die  into  ribands. 
It  is  then  dried  at  50°  C.,  and  finally  frequently  washed  with 
water  to  reduce  the  amount  of  solvent. 

The  powder  is  decidedly  porous,  and  several  disastrous 
explosions  have  been  attributed  to  its  spontaneous  com- 
bustion, the  most  notable  of  which  were  the  total  destruc- 
tion of  two  battleships,  the  lena  in  1907  and  the  Libert e  in 
1911. 


82  EXPLOSIVES 

SHOT-GUN  SMOKELESS  PROPEU,ANTS 

Much  quicker  burning  powders  are  necessary  for  use  with 
shot  guns  than  with  rifled  arms,  and  in  order  to  produce  a 
good  pattern,  i.e.  in  order  that  the  shot  may  not  spread 
unduly,  comparatively  little  pressure  must  be  present  at 
the  moment  that  the  charge  leaves  the  muzzle. 

Almost  all  shot-gun  smokeless  propellants  are  nitro- 
cellulose powders  to  which  as  a  rule  a  certain  amount  of 
barium  or  potassium  nitrate  has  been  added,  and  they  may 
be  roughly  divided  into  two  classes,  viz.  condensed  powders 
and  bulk  powders.  The  former  are  completely  gelatinized 
powders  and  are  made  by  methods  very  similar  to  those 
used  for  rifle  propellants,  the  necessary  increased  rate  of 
combustion  being  attained  by  forming  them  into  thin  flakes 
or  small  grains.  Munroe  describes  the  manufacture  as 
being  carried  out  in  the  United  States  as  follows  : — 

Finely  pulped  wet  nitrocellulose  is  mechanically  agitated 
with  water  containing  5  per  cent,  of  barium  nitrate  and  2 
per  cent,  of  potassium  nitrate  in  a  vertical  jacketed  pan. 
An  emulsion  of  amyl  acetate  and  water  containing  barium 
and  potassium  nitrate  is  then  added,  and  granulation  allowed 
to  take  place  at  the  ordinary  temperature  for  a  few  minutes, 
after  which  steam  is  turned  into  the  jacket  and  agitation 
and  heating  continued  for  5-6  hours,  during  which  time 
most  of  the  amyl  acetate  and  some  water  distil  off  and  are 
condensed.  The  contents  of  the  vessel  are  then  run  out 
and  the  grains  dried  and  sieved,  oversized  and  undersized 
grains  being  added  to  the  next  charge  in  the  proportion 
of  250  Ibs.  of  waste  to  450  Ibs.  of  fresh  nitrocellulose. 

Another  American  sporting  powder,  Indurite,  is  made 
from  guncotton,  the  soluble  portion  being  first  extracted 
with  methyl  alcohol  and  the  residue  then  gelatinized  with 
nitrobenzole,  this  latter  being  finally  removed  by  treatment 
with  hot  water. 

One  of  the  great  disadvantages  of  condensed  powders 
lies  in  the  fact  that  owing  to  their  small  bulk  they  require 
special  cartridge  cases.  Also  in  loading  cartridges  the 


SMOKELESS  PROPELLANTS  83 

powder  is  always  measured  out,  and  consequently  the  higher 
the  density  of  the  powder  the  greater  is  the  error  in  weight 
due  to  slight  differences  in  volume.  For  this  reason  "  bulk  " 
powders  are  usually  preferred  to  the  condensed  powders. 
These  are  composed  of  grains  of  nitrocellulose,  with  or 
without  the  addition  of  small  quantities  of  other  substances, 
the  grains  being  gelatinized  on  the  surface.  Such  bulk 
powders  are  known  as  42 -grain  and  33 -grain  powders, 
meaning  that  the  charge  for  a  12-bore  gun  is  42  and  33 
grains  respectively,  and  that  the  volume  occupied  by  this 
amount  is  the  same  as  that  of  the  standard  black  powder 
charge,  viz.  3  drams.  Thirty-grain  powders  are  also  made, 
but  in  these  gelatinization  is  almost  complete,  so  that  they 
are  more  in  the  nature  of  condensed  powders. 

Most  shot-gun  powders  contain  barium  and/or  potassium 
nitrate,  and  in  many  cases  it  is  found  best  to  incorporate  a 
much  greater  quantity  than  is  desired  in  the  finished  powder, 
the  excess  being  subsequently  removed  by  dissolving  out 
with  water.  This  yields  a  more  bulky  powder,  and  facilitates 
the  production  of  one  having  a  correct  weight  for  a  given 
volume. 

The  nitrocellulose  used  for  shot-gun  powders  usually  con- 
tains from  12 '0  to  12 '8  per  cent,  of  nitrogen,  but  the  nitrogen 
content  of  nitrolignite  powders  is  frequently  lower  than  this. 

The  first  process  in  manufacturing  bulk  powders  is 
graining  the  nitrocellulose.  This  can  be  done  in  several 
ways,  such  as  grinding  in  edge  runners  while  wet  or  in  ball 
mills,  the  balls  being  made  of  lignum  vitse.  During  this 
process  the  other  ingredients,  such  as  nitrates,  are  added 
and  the  incorporating  continued  until  mixing  is  complete 
and  the  grains  are  judged  to  be  suitable  for  the  class  of 
powder  desired.  They  are  then  roughly  sifted  and  dried 
in  stoves  at  a  low  temperature.  After  drying  they  are 
again  sifted  to  remove  dust  and  then  gelatinized  on  the 
surface.  This  is  effected  in  revolving  drums  provided  with 
ridges  so  as  to  keep  the  powder  in  motion.  The  solvent 
is  generally  sprayed  in,  as  if  added  in  bulk  it  does  not  become 
evenly  distributed,  with  the  result  that  some  of  the  grains 


84  EXPLOSIVES 

remain  ungelatinized,  while  others  become  overgelatinized 
and  may  adhere  together  and  form  lumps.  After  spraying 
and  thorough  mixing  so  as  to  ensure  even  distribution  of 
the  solvent,  the  grains  are  allowed  to  steep  for  a  few  hours 
and  then  dried.  The  drying  is  best  carried  out  in  two 
stages,  as  during  the  later  stages  the  amount  of  solvent 
given  off  is  so  small  that  it  is  not  worth  recovering.  In 
order  to  recover  as  much  solvent  as  possible,  the  first  part 
of  the  drying  is  carried  out  in  revolving  drums  in  vacuo, 
the  vacuum  pump  being  connected  with  the  hollow  spindle 
of  the  drum  through  a  copper  coil  condenser  cooled  with 
chilled  brine.  A  fine  gauze  is  interposed  between  the  drum 
and  the  condenser  in  order  to  prevent  dust  being  carried 
over  mechanically.  In  order  to  guard  against  pressure 
being  set  up  in  the  drum  through  the  condenser  becoming 
frozen  or  the  dust  filter  choked,  the  cover  of  the  charging 
hole  is  held  in  position  by  the  vacuum  only,  so  that  should 
the  vacuum  fail  it  falls  off  and  at  once  releases  any  pressure. 
After  as  much  as  possible  of  the  solvent  has  been  recovered, 
the  powder  is  removed  to  stoves  and  the  drying  completed 
by  spreading  it  in  thin  layers  on  shallow  trays,  no  attempt 
being  made  to  recover  solvent,  as  it  is  given  off  too  slowly. 
When  drying  is  complete  the  powder  is  again  sifted  to 
remove  oversized  and  undersized  grains  and  then  allowed 
to  age  for  about  six  weeks.  The  ageing  period  is  necessary 
in  order  that  the  powder  may  take  up  a  certain  amount  of 
moisture  from  the  atmosphere,  and  reach  the  state  in  which 
it  will  be  used.  The  ballistic  properties  of  each  batch  are 
then  tested,  and  the  various  batches  carefully  blended  so  as 
to  produce  a  powder  with  standard  properties.  This  blending 
is  most  essential  if  different  lots  of  the  same  powder  are  to 
produce  the  same  effect  in  use.  The  production  of  30-grain 
powders  involves  the  use  of  nitrocellulose  with  a  high  nitro- 
gen content  in  order  that  the  smaller  weight  of  powder  may 
produce  the  same  power,  and  to  reduce  the  rate  of  burning 
gelatinization  must  be  complete.  At  the  same  time  the 
bulk  of  the  powder  must  be  maintained  in  order  that  a 
30-grain  charge  may  occupy  the  standard  volume  of  3  drams. 


SMOKELESS   PROPELLANTS  85 

This  is  effected  by  incorporating  the  nitrocellulose  with 
several  times  its  weight  of  barium  or  potassium  nitrate, 
and  then  drying  and  gelatinizing  freely.  The  dough  is 
then  pressed  in  much  the  same  way  as  a  condensed  powder, 
and  after  drying  the  nitrate  is  almost  completely  removed 
by  treatment  with  warm  water.  The  same  method  is  used 
in  making  33-grain  powders,  although  the  gelatinization  is 
not  so  complete. 

As  regards  the  solvents  used  in  preparing  bulk  powders, 
acetone  alone  is  not  very  suitable,  as  it  produces  a  brittle 
colloid.  It  is,  however,  used  sometimes  in  conjunction 
with  alcohol.  Alcohol-ether  mixture  gives  excellent  results, 
but  is  very  difficult  to  recover.  Ethyl  acetate  and  amyl 
acetate  are  both  used  to  a  large  extent  either  alone  or  in 
conjunction  with  other  solvents,  and  the  use  of  benzole  has 
also  been  proposed.  Sometimes  an  aromatic  nitrohydro- 
carbon,  such  as  dinitrobenzole  or  dinitrotoluol  or  trinitrotoluol, 
is  added  to  the  solvent  in  order  to  assist  the  gelatinization. 
Such  compounds  naturally  remain  in  the  powder,  and  con- 
sequently when  used  sufficient  nitrate  for  their  combustion 
must  be  added.  A  certain  amount  of  an  organic  dyestuff , 
such  as  aurine,  is  also  generally  added  to  the  solvent  in 
order  to  improve  the  appearance  of  the  powder.  In  some 
cases  also  a  solution  of  collodion  is  added,  so  as  to  varnish 
the  outsides  of  the  grains.  This  makes  them  somewhat 
less  liable  to  take  up  moisture,  and  at  the  same  time  slows 
down  the  rate  of  combustion.  This  latter  is  also  effected  by 
glazing  the  finished  powder  by  rumbling  with  a  little  graphite. 
The  table  on  page  86  shows  the  composition  of  a  few  well- 
known  sporting  powders  manufactured  in  this  country. 

Of  the  33-grain  powders,  Smokeless  Diamond  is  probably 
the  most  used  in  this  country.  It  chiefly  consists  of  nitro- 
cellulose and  barium  nitrate,  the  grain  being  glazed  with 
graphite. 

Schultze  Powder,  which  was  one  of  the  earliest  smokeless 
shot-gun  propellants,  is  a  nitro-lignine  powder  and  is  made 
from  wood.  The  wood  is  first  carefully  purified  to  free  it 
as  far  as  possible  from  pectose  and  non-cellulosic  substances. 


86 


EXPLOSIVES 


and  then  nitrated.  After  washing  the  nitro-lignine  is 
impregnated  with  barium  nitrate,  and  the  grains  then  gela- 
tinized on  the  surface  and  hardened  by  spraying  with  ethyl- 
alcohol  or  other  suitable  solvent.  Schultze  Powder  has 
always  been  a  favourite  with  sportsmen  for  use  with  the 
shot  gun,  but  up  to  the  present  nitro-lignine  has  not  been 
found  suitable  for  use  with  rifled  arms.  Probably  the 
German  Government  has  evolved  some  method  of  rendering 
it  suitable,  as  the  Allied  blockade  cut  off  the  supply  of  cotton. 


Imperial 
Schultze. 

Amberite. 

E.C. 

Schultze. 

Kyroch's     Sporting 
Smokeless.  Ballistite. 

N.G.  .. 

_ 

_ 

_ 

37-6 

N.C.  .. 

.  —  - 

71 

79 

62-1 

52-1          62-3 

Nitro-lignin 

80-1 

— 

D.N.T. 

— 

— 

— 

— 

I9'5 

KN03 



I  "2 

4'5 

1-8 

Ba(N03)2 

10-2 

18-6 

7'5 

26-1 

22*2 

Camphor 

— 

—  . 

— 

i         

W.M. 



**4 

3-8 

— 

2*7 

M.J.  .. 

7*9 

5'8 



4'9 

—                — 

Starch 

— 

— 

3'5 

—                — 

Carbon 





—                — 

Ash   .. 

—  . 

— 

. 

— 

'9 

Volatile 

1-8 

2 

l-l 

1-6 

I  '2 

Schultze  cube  Powder  is  a  30-grain  fully  gelatinized 
powder,  and  is  probably  derived  from  cotton  or  wood  pulp. 
In  France,  where  the  manufacture  of  explosives  is  a  State 
monopoly,  the  following  sporting  powders  are  provided  : — 


Poudre  S. 

Poudre  J. 

Poudre  M. 

Poudre  T. 

N.C  

65 

83 

71 

TOO 

Ba(N03)2 

29 

20 



KN03     .. 

6 

— 

5 

Am2Cr2O7 

— 

M 

— 

K2Cr207 

— 

3 

—               — 

Camphor 

1 

3 

— 

Gelose    .. 

— 

— 

i 

— 

Number  of  grains  per  gram 
Charge  for  1  6-calibre  gun  wit 

h 

1000 

250-300 

3500            2500 

30  grams  No.  6  shot 

2-4                  2-8 

2'I                 I'Q 

Density 

•500           -750 

'475 

•565 

Mean  pressure,  Kg.  per  cm.  2 

445 

35° 

5OO 

47° 

SMOKELESS  PROPELLANTS  87 

Poudre  T  bis  is  very  similar  to  Poudre  T,  but  is  rather 
quicker. 

Poudre  S  is  made  by  mixing  the  ingredients  wet  under 
light  edge  runners  and  then  drying  and  incorporating  with 
ethyl-alcohol,  the  dough  being  formed  into  grains  by  passing 
it  through  a  sieve.  It  produces  a  great  deal  of  fouling. 

Poudre  J  is  made  by  incorporating  the  nitrocellulose  with 
ether-alcohol  and  very  finely  ground  bichromates  and  then 
rolling  out. 

Poudre  M  is  made  in  much  the  same  way  as  Poudre  S, 
but  the  grains  receive  a  final  treatment  with  ether-alcohol 
in  which  camphor  and  collodion  are  dissolved.  It  is  a  powder 
which  is  apt  to  develop  excessive  pressures. 

Poudre  T  contains  no  nitrate  or  bichromate,  and  the 
gelatinization  is  brought  about  by  a  mixture  of  ethyl  acetate 
and  acetone. 

Of  the  Belgian  sporting  powders,  Mullerite,  which  contains 
no  mineral  salts,  and  Clermonite,  which  is  a  mixture  of  nitro- 
cellulose and  barium  and  potassium  nitrate,  are  the  best  knowni 

Several  German  powders  have  acquired  a  good  reputa- 
tion. Among  them  may  be  mentioned  Fasan  and  Tiger, 
which  are  roughly  42-grain  powders ;  Rothweil  and  Walsrode, 
33-grain  powders ;  and  Saxonia  and  Adler-Marke,  30-grain 
powders.  They  are  made  in  much  the  same  way  as  the 
corresponding  British  powders.  Walsrode  is  gelatinized  with 
ethyl  acetate. 

AUPHATIC  SOLVENTS 

The  solvents  used  in  the  manufacture  of  smokeless  pro- 
pellants  are  expensive  and  add  considerably  to  the  cost  of 
manufacture.  Alcohol  up  to  the  present  has  been  obtained 
by  the  fermentation  of  sugars  or  starches,  molasses,  potato 
and  maize  being  the  chief  raw  materials.  Recently,  how- 
ever, sawdust  and  the  sulphite  liquor  obtained  as  a  waste 
product  in  the  manufacture  of  paper  pulp  has  been  used,  as 
on  hydrolysis  with  acids  the  cellulosic  substances  are  broken 
down  into  fermentable  sugars.  Considerable  difficulties  have 
been  met  with  in  carrying  out  the  process  on  a  commercial 


88  EXPLOSIVES 

scale,  but  these  are  gradually  being  overcome,  and  a  good 
deal  of  attention  is  being  paid  to  the  subject  in  the  United 
States.  A  purely  synthetic  process  is  also  in  course  of 
development,  and  consists  in  converting  acetylene  into 
acetaldehyde  and  then  reducing  this  to  alcohol. 

Ether  has  usually  been  manufactured  by  the  action  of 
sulphuric  acid  on  alcohol,  but  probably  the  catalytic  de- 
hydration of  alcohol  will  prove  to  be  a  less  costly  process  in 
the  future. 

Acetic  acid,  used  for  the  manufacture  of  ethyl  acetate 
and  acetone,  is  usually  obtained  as  a  by-product  in  the 
carbonization  of  wood.  Unfortunately  coniferous  woods  are 
quite  unsuited  for  the  purpose,  and  even  with  hard  woods 
the  yield  is  very  poor.  Here  again  attempts  are  being  made 
with  considerable  success  to  introduce  purely  synthetic 
methods.  In  these  the  starting  out  substance  is  acetylene, 
which,  when  treated  with  sulphuric  acid  in  the  presence  of 
mercuric  sulphate,  takes  up  water  and  passes  into  acetalde- 
hyde, this  being  readily  oxidized  to  acetic  acid— 

CH  CH3  CH3 

III       ->l->| 

CH  CHO  COOH 

The  process  is  an  old  one,  but  it  is  only  during  the  last  two 
or  three  years  that  any  success  has  been  achieved,  and  it  is 
still  too  early  to  predict  to  what  extent  the  process  is  likely 
to  come  into  general  use.  One  of  the  great  troubles  is  the 
tendency  of  the  aldehyde  to  polymerize  the  resinous  sub- 
stances. 

Acetone  has  generally  been  manufactured  by  the  dry 
distillation  of  calcium  acetate,  this  decomposing  at  300°  C. 
into  the  carbonate  and  acetone — 

(CH3CO)  2Ca  =CaC03 + (CH3)  2CO 

Acetone,  accompanied  by  fusel  oil,  can,  however,  also  be 
obtained  by  the  fermentation  of  starch,  and  seaweed  and 
horse-chestnuts  also  appear  suitable  for  the  purpose.  In 
Great  Britain  a  company  was  floated  in  1912  to  work  the 
process,  the  primary  object,  however,  being  to  obtain  the 


SMOKELESS  PROPELLANTS  89 

fusel  oil  and  from  it  synthetic  rubber.  This  latter  part  of 
the  scheme  does  not  seem  to  have  been  a  success,  but  the 
company  has  produced  acetone  for  war  purposes.  In  the 
United  States  a  large  plant  for  the  fermentation  of  seaweed 
has  been  put  down  by  the  Herculose  Powder  Company  on 
the  Pacific  sea-board,  potash  being  obtained  amongst  other 
things  as  a  by-product,  and  in  Great  Britain  experimental 
work  has  been  done  at  Penzance  in  Cornwall.  In  these 
processes  the  residues,  after  the  extraction  of  the  valuable 
products,  are  burnt  in  gas  producers  and  so  furnish  a  large 
percentage  of  the  heat  required  for  running  the  works. 
Iodine  and  bromine  are  also  recovered,  but  for  this  purpose 
the  weed  should  be  cut  from  the  sea  bottom  at  a  considerable 
depth,  as  that  washed  up  on  to  the  shore  is  comparatively 
poor  in  these  elements. 

LITERATURE 

The  manufacture  of  Cordite  is  described  in  detail  in  "Treatise  on 
Service  Explosives,"  1907,  published  by  Authority,  and  an  illustrated 
description  of  the  New  Explosives  Company's  Cordite  plant  appeared  in 
Arms  and  Explosives,  1898,  p.  242. 

Litigation  on  the  Cordite  patents  is  referred  to  in  A.E.,  1897,  pp.  89, 
106,  116,  172. 

The  manufacture  of  the  United  States  Military  Smokeless  Powder  is 
given  in  detail  by  E.  C.  Worden  in  "Nitrocellulose  Industry,"  vol.  ii., 
1911  ;  and  also  in  the  Journal  of  the  United  States  Artillery,  1910,  p.  140. 

The  use  of  nitromethane  for  assisting  gelatinization  is  covered  by 
F.P.  394,992.  The  addition  of  nitroguanidine  for  reducing  the  tempera- 
ture of  explosion  is  covered  by  U.S.P.  899,855,  and  the  use  of  tartrates 
for  the  same  purpose  by  E.P.  I5,56506. 

Producing  flaked  powders  with  knobs  or  ribs  to  prevent  the  flakes 
lying  face  to  face  is  the  subject  of  E.P.  I2,89206,  2I.77905. 

Experiments  on  the  stability,  or  lack  of  stability,  of  Poudre  B  are 
described  in  P.5.,  xv.,  i;  5.5.,  1910,  pp.  345,  369,  389;  1911,  pp.  303, 
327,  441,  464. 

Vielle's  experiments  on  erosion  are  described  in  P.5.,  xi.  157. 

Smokeless  propellants  in  general  are  discussed  in  5.5.,  1913,  pp.  126, 
2^5,  307,  330,  352,  and  the  relative  merits  of  nitroglycerine  and  nitro- 
cellulose propellants  in  5.5.,  1913,  pp.  368,  393. 

Experiments  on  the  behaviour  of  smokeless  propellants  when  burnt 
in  quantities  of  from  i  to  10  tons  are  described  with  photographs  in  5.5., 
1914,  PP.  187,  217. 

A  large  number  of  works  on  interior  and  exterior  ballistics,  most  of 
them  more  or  less  mathematical,  have  been  published  from  time  to  time, 
but  the  following  can  be  recommended : — 

J.  M.  Ingalls,  "  Interior  Ballistics,"  New  York,  1912. 

C.  Cranz,  "Lehrbuchder  Ballistik,"  3  vols.,  Berlin,  1910-1913. 

P.  Charbonniere,  "Balistique  Interieure,"  Paris,  1908. 

A.  C.  Crehore  and  G.  O.  Squier,  "  Polarizing  Photo-Chronograph," 
New  York,  1897. 


SECTION  IV.-BLASTING  EXPLOSIVES 

FOR  blasting  hard  rock  a  powerful  and  brisant  explosive 
is  required,  more  especially  in  operations  such  as  tunnelling, 
where  it  is  not  required  to  obtain  the  material  in  large 
pieces,  and  an  explosive  with  high  density  is  also  desirable 
for  this  class  of  work,  as  the  cost  of  making  bore  holes  in 
hard  material  is  very  considerable.  Softer  minerals  require 
a  slower  burning  explosive,  as  otherwise  they  are  shattered 
too  much  and  excessive  amounts  of  dust  are  produced. 
For  this  reason  and  on  account  of  its  cheapness,  gunpowder 
is  still  extensively  used  for  quarrying.  For  work  in  coal 
mines  a  mild  explosive  is  required  for  coal  getting  in  order 
that  the  material  shall  not  be  unduly  shattered,  and  a  more 
brisant  explosive  for  ripping  and  clearing  away  stone.  At 
the  same  time  the  explosive  used  must  not  fire  the  mine 
gases  nor  cause  a  coal-dust  explosion.  Explosives  for  use 
in  fiery  mines  are  known  in  this  country  as  Permitted 
Explosives,  and  are  treated  in  the  next  section. 

For  use  in  wet  situations  a  satisfactory  blasting  explosive 
should  not  be  readily  spoilt  by  water,  although  this  trouble 
can  be  largely  got  over  by  using  waterproof  wrappers. 
Finally,  as  blasting  explosives  are  largely  used  by  ignorant 
people,  they  should  be  as  fool-proof  as  possible.  Explosives 
containing  nitroglycerine  are  liable  to  freeze,  and  in  this 
state  are  difficult  to  detonate.  There  is  a  statutory  obliga- 
tion to  thaw  out  such  explosives  before  use  in  a  proper 
warming  pan,  but  in  spite  of  this  accidents  occur  every 
year  through  miners  thawing  out  frozen  explosives  over  a 
fire.  The  warming  pans  are  very  simple  in  construction 
and  consist  of  felt-covered,  double-walled  tin-plate  vessels, 
the  explosive  being  placed  in  the  inner  vessel  and  warm 
water  in  the  annular  space.  By  their  use  explosives  can 


BLASTING  EXPLOSIVES  91 

be  thawed  in  safety,  but  the  process  takes  time,  and  to  some 
minds  the  temptation  to  thaw  over  a  fire  seems  irresistible. 

Except  in  the  case  of  very  heavy  charges,  the  danger 
from  fumes  is  not  great  when  surface  blasting  is  carried  on, 
but  in  underground  workings  the  case  is  different.  The 
poisonous  fumes  that  result  from  the  detonation  of  an 
explosive  include  carbon  monoxide,  due  in  part  to  lack  of 
oxygen  and  in  part  to  the  paper  wrapper.  L,ack  of  oxygen 
in  the  explosive  mixture  can  be  remedied  by  the  addition 
of  more  oxidizing  agent,  but  it  is  not  safe  to  remove  the 
wrapper  before  inserting  the  cartridge  into  the  bore  hole. 
Metal  foil  wrappers  might  be  substituted  for  paper,  but  this 
would  only  be  changing  one  evil  for  another,  as  the  metallic 
oxide  in  itself  would  be  objectionable  unless  aluminium  or 
tinfoil  were  used.  The  only  satisfactory  safeguard  would 
seem  to  lie  in  ample  ventilation.  Explosives  containing 
barium  or  lead  salts  give  off  poisonous  fumes  due  to  the 
salts  of  these  metals,  and  ammonium  perchlorate  explosives 
are  very  liable  to  evolve  chlorine  unless  alkali  nitrate  is  also 
present  in  sufficient  quantity  to  provide  a  base  for  the 
chlorine  to  unite  with.  Finally,  explosives  containing  nitro- 
aromatic  hydrocarbons  may  give  off  poisonous  fumes  of 
these  if  detonation  is  incomplete  through  insufficient  oxygen 
or  through  the  use  of  too  weak  a  detonator. 

All  composite  blasting  explosives  consist  of  an  oxidizing 
agent  and  oxidizable  matter,  any  or  none  of  which  may  be 
explosives  in  themselves.  In  gunpowder,  for  example,  the 
sulphur  and  charcoal  provide  the  combustible  matter  and 
the  nitre  the  oxidizing  agent,  none  of  these  being  capable 
of  explosion  alone.  Blasting  Gelatine,  on  the  other  hand, 
consists  of  nitrocellulose  as  combustible  matter  and  nitro- 
glycerine as  an  oxidizing  agent,  both  these  ingredients 
being  capable  of  exploding  alone.  An  intermediate  stage 
is  represented  by  Gelignite,  in  which  an  explodable  and 
a  non-explodable  oxidizing  agent  (nitroglycerine  and  potas- 
sium nitrate)  is  used  in  conjunction  with  explodable  and 
non-explodable  combustible  matter  (nitrocellulose  and 
wood  meal). 


92  EXPLOSIVES 

The  following  list  gives  the  chief  oxidizing  agents  avail- 
able industrially,  together  with  the  maximum  amount  of 
available  oxygen  per  100  grams  : — 

N.G.  ..3'5           I      KC103     ..  ..37 

KNO3  . .  40  NaClO3  . .  . .     45 

NaNO3  ..  47  KC1O4     ..  ..46 

AmNO3  . .  20  NaClO4  . .  . .     52 

Ba(NO3)2  . .  30        ,  AmClO4  . .     27 

Pb(NO3)2  . .  24  (PbO)  Ba(ClO4)2  . .     38 

Pb(N03)2  . .  29  (Pb) 

Of  these  it  should  be  noted  that  nitroglycerine,  ammonium 
nitrate,  and  ammonium  perchlorate  are  all  capable  of  being 
exploded,  although  ammonium  nitrate  is  only  exploded 
with  difficulty.  The  chlorates  are  also  capable  of  exploding, 
as  they  are  endothermic  compounds  and  one  or  two  accidents 
have  been  due  to  chlorate  explosions. 

A  large  number  of  combustible  matters  is  available,  of 
which  the  following  are  the  most  important  :— 

Nitrocellulose. 

Dinitrobenzole. 

Di-  an4  tri-nitrotoluol. 

Mono-  di-  and  tri-nitronaphthalene. 

Wood  meal. 

Charcoal. 

To  a  lesser  extent  starch,  flour,  potato  meal,  and  the 
like  are  also  used,  as  they  help  the  resulting  mixture  to  bind 
together.  Castor  oil  enters  into  the  composition  of  certain 
chlorate  mixtures,  as  it  renders  them  less  sensitive  to  shock. 

Finally,  inert  substances  such  as  kiesselguhr,  silica,  mica, 
etc.,  are  used  for  absorbing  nitroglycerine  in  some  explosives 
such  as  Dynamite,  and  neutral  salts  such  as  sodium  chloride 
are  used  as  "coolers  "  in  Permitted  Explosives. 

Blasting  explosives,  other  than  black  powder,  can  be 
roughly  divided  into  four  classes,  viz. :  (i)  Dynamite  and 
its  Congeners ;  (2)  Gelatinized  Explosives ;  (3)  Chlorate 
Mixtures  ;  (4)  Ammonium  Nitrate  Explosives.  The  division 
is  not  a  very  sharp  one,  but  is  the  most  convenient  method 
of  classification, 


BLASTING  EXPLOSIVES  93 

DYNAMITE  AND  ITS  CONGENERS 

When  Nobel  first  introduced  nitroglycerine  as  a  blasting 
explosive  it  was  used  in  the  liquid  form,  but  was  frequently 
transported  in  a  frozen  condition  in  order  to  minimize  the 
danger.  In  spite  of  all  precautions,  however,  numerous 
accidents  occurred,  so  that  the  transport  of  nitroglycerine 
either  in  the  liquid  or  in  the  frozen  state  was  soon  forbidden. 
This  caused  Nobel  to  seek  some  inactive  substance  that 
would  absorb  the  oil  and  render  its  conveyance  and  use 
safe  without  interfering  with  its  explosive  properties.  He 
found  kiesselguhr,  a  form  of  siliceous  earth  found  in  Germany, 
Austria,  Norway,  Australia,  and  Scotland,  to  be  most  suitable, 
as  good  qualities  will  take  up  three  times  their  weight  of 
nitroglycerine  and  still  remain  dry  ;  but  in  his  patent  he  also 
claimed  the  use  of  other  materials  such  as  ground  brick, 
dry  plaster,  etc.  He  named  the  explosive  thus  obtained 
Dynamite. 

Kiesselguhr,  or  guhr  as  it  is  usually  called,  varies  very 
much  in  quality,  some  samples  being  quite  unsuited  for 
Dynamite  manufacture  owing  to  their  very  poor  absorptive 
power  or  high  content  of  sand.  The  content  of  organic 
matter  is  also  very  variable,  running  from  4-5  per  cent,  to 
as  high  as  35  or  40  per  cent,  in  the  case  of  many  of  the 
Scotch  deposits.  In  any  case,  the  guhr  requires  to  be 
thoroughly  calcined  before  use  in  order  to  burn  this  off, 
and  must  then  be  sifted  through  a  3O-mesh  sieve  in  order 
to  get  rid  of  sand.  This  latter  process  is  absolutely  essential, 
as  grains  of  sand  would  give  rise  to  undue  friction  when 
making  up  the  cartridges  and  might  well  cause  an  explo- 
sion. After  calcining  the  guhr  usually  has  a  pink  colour 
due  to  oxide  of  iron,  but  some  samples  are  almost  white, 
and  when  this  is  the  case  most  manufacturers  add  a  little 
red  ochre  in  order  that  the  finished  Dynamite  may  have 
the  characteristic  red-brown  colour. 

The  manufacture  of  Dynamite  is  carried  out  as  follows  : 
The  guhr  is  weighed  out  after  sieving  into  wooden  boxes 
or  rubber  bags  and  taken  to  the  nitroglycerine  department, 


94  EXPLOSIVES 

where  the  requisite  quantity  of  nitroglycerine  is  measured 
out  and  added.  The  boxes  or  bags  are  then  carried  to  the 
mixing  house,  where  they  are  emptied  out  into  lead  tanks 
and  the  contents  thoroughly  mixed.  This  can  be  done  by 
hand  by  rubbing  the  loose  Dynamite  repeatedly  through  a 
coarse  sieve  (about  8-mesh),  or  after  a  rough  mixing  by 
hand  the  loose  Dynamite  can  be  transferred  to  a  Werner 
and  Pfleiderer  mixing  machine  (Fig.  15,  p.  75)  and  mixing 
then  completed  mechanically.  The  resulting  powder  should 
not  feel  moist,  but  at  the  same  time  it  must  not  be  too  dry 
or  it  will  not  bind  properly  in  the  dynamite  pumps  and  will 
not  detonate  easily  in  use.  If  too  moist  more  guhr  can 
be  added  or  from  '5  to  i  per  cent,  of  barium  sulphate  can 
be  mixed  in,  as  this  lowers  the  absorptive  capacity  of  the 
guhr.  If  too  dry  more  nitroglycerine  must  be  added. 
With  a  little  experience  it  is  easy  to  judge  whether  the 
explosive  is  of  the  right  consistency  or  not.  Dynamite 
mixing  is  an  extremely  unpleasant  occupation  for  those 
not  used  to  it,  as  the  dusty  explosive  enters  the  mouth  and 
nose  and  causes  very  severe  headache.  Those  engaged 
continuously  in  the  process  as  a  rule  get  acclimatized,  but 
when,  as  is  often  the  case,  the  explosive  is  only  manufactured 
intermittently  the  workers  suffer  severely,  even  those  who 
have  been  used  to  handling  nitroglycerine  jellies  getting 
headache  at  first  when  put  on  to  Dynamite. 

For  converting  the  loose  Dynamite  into  cartridges  the 
Guttmann  dynamite  pump  (Fig.  16)  is  almost  universally 
used.  It  consists  of  a  plunger  working  vertically  between 
two  loose  guides,  motion  being  imparted  by  a  horizontal 
lever.  The  end  of  the  plunger  is  shod  with  lignum  vitae 
and  works  in  a  brass  tube  of  the  same  diameter  as  the 
finished  cartridge,  plenty  of  clearance  being  allowed  between 
the  plunger  and  the  brass  tube  so  as  to  avoid  friction. 
The  upper  end  of  the  brass  tube  is  fixed  into  a  brass  block, 
usually  covered  with  leather,  to  which  is  attached  the  lower 
end  of  a  conical  bag  made  of  cloth  or  light  leather.  The 
upper  and  wider  end  of  this  bag  is  attached  to  a  boss  further 
up  the  plunger  by  means  of  three  strings,  so  that  at  each 


BLASTING  EXPLOSIVES 


95 


upward  stroke  of  the  plunger  the  bag  gets  a  jerk.  An 
inverted  bell  is  fixed  to  the  plunger  just  above  the  bag,  so 
as  to  prevent  explosive  working  up  into  the  guides. 

In  pumping  cartridges  the  loose  Dynamite  is  fed  into 
the  bag  with  a  wooden  scoop,  and  the  plunger  then  worked 
up  and  down  by  hand.  Bach  upward  stroke  jerks  some  of 
the  powder  into  the  brass  tube,  which  the  following  down- 


FIG.  1 6. — Dynamite  Pump. 

ward  stroke  compresses  into  a  more  or  less  coherent  mass 
which  issues  at  the  lower  end  as  a  rod.  This  is  broken  off 
from  time  to  time  and  wrapped  in  parchment  paper.  The 
most  usual  diameters  for  Dynamite  cartridges  are  f  in.  and 
|  in.,  and  the  most  usual  weight  2  oz.  Ordinary  Dynamite, 
consisting  of  75  per  cent,  of  nitroglycerine  and  25  per  cent, 
of  guhr,  with  the  possible  addition  of  small  quantities  of 


96 


EXPLOSIVES 


ochre  for  colouring,  or  a  trace  of  calcium  or  magnesium 
carbonate  to  render  it  more  stable,  is  known  in  Europe 
as  Dynamite  No.  i  to  distinguish  it  from  the  less  powerful 
Dynamites  formerly  made  to  some  extent,  viz.  Dynamite 
No.  2,  consisting  of  18  per  cent,  of  nitroglycerine,  10  per 
cent,  of  carbon,  and  72  per  cent,  of  nitre ;  and  Dynamite 
No.  3,  consisting  of  37*5  per  cent,  of  nitroglycerine,  12*5 
per  cent,  of  guhr,  and  25  per  cent,  each  of  wood  meal  and 
nitre.  In  the  United  States,  however,  guhr  Dynamite 
goes  by  the  name  of  Giant  Powder,  the  name  Dynamite 
being  reserved  for  mixtures  of  nitroglycerine,  wood  meal, 
and  sodium  nitrate. 

In  France,  in  addition  to  guhr  Dynamite,  Dynamites 
are  also  made  from  a  mineral  called  randanite,  composed 
of  weathered  felspar,  with  or  without  the  addition  of 
absorbent  silica  either  from  natural  sources  or  manufactured 
by  passing  silicon  fluoride  into  water.  The  Government 
factory  at  Vonges,  for  example,  makes  the  following 
grades : — 


No.  x. 

No.  2. 

No.  3. 

Special. 

1 

N.G  75 

5°                  3° 

90 

Randanite             .  .          .  .             20-8 

I 

I 

Silica          3*3 

48 

65 

8 

MgCOs       !             '4 

— 

— 

i 

CaC03        

i  '5 

I 

—  . 

Ochre          

'5 

5 

—  - 

Slag 

_ 

4 

In  Spain  mica  is  sometimes  used  as  an  absorbent,  the 
product  containing  42  per  cent,  of  nitroglycerine. 

Dynamite  had  a  great  vogue  when  first  introduced,  but 
is  comparatively  little  used  now  as  it  has  been  largely 
replaced  by  gelatinized  explosives,  although  there  is  still 
a  fair  demand  for  it.  It  freezes  more  easily  than  nitro- 
glycerine, and  in  the  frozen  state  is  difficult  to  detonate. 
It  is  very  brisant  in  nature,  and  has  the  great  dis- 
advantage that  in  contact  with  water  the  nitroglycerine  is 
displaced. 


BLASTING   EXPLOSIVES 


97 


In  order  to  utilize  the  excess  of  oxygen  present  in  nitro- 
glycerine many  powders  have  been  made  in  which  a  com- 
bustible absorbent  has  been  used  in  place  of  guhr.  Charcoal 
made  from  cork  has  great  absorptive  power,  and  an  explosive 
consisting  of  90  per  cent,  of  nitroglycerine  and  10  per  cent, 
of  cork  charcoal  was  manufactured  at  one  time  under  the 
name  of  Carbo-dynamite.  It  was  too  violent  and  expensive 
for  most  purposes,  however,  and  wood  meal  is  more  usually 
employed.  Atlas  Powder,  for  example,  consists  of  nitro- 
glycerine 75  and  wood  meal  21  per  cent.,  the  balance  being 
made  up  of  chalk  with  or  without  the  addition  of  a  little 
sodium  nitrate. 

These  wood  meal  Dynamites  are  deficient  in  oxygen,  and 
in  order  to  supply  this  deficiency  nitrates  are  added.  This 
class  of  explosive  has  become  extremely  popular  in  the 
United  States,  where  many  blasting  explosives  are  made 
consisting  of  varying  quantities  of  nitroglycerine,  wood 
meal,  and  sodium  or  ammonium  nitrate.  Sodium  nitrate  is 
preferred  to  the  potassium  salt  on  account  of  its  lower  price, 
but  it  is  decidedly  hygroscopic,  and  ammonium  nitrate  is 
still  more  so,  so  that  these  explosives  readily  take  up  water 
which  in  turn  displaces  the  nitroglycerine.  For  this  reason 
they  have  never  come  into  use  in  this  country. 

The  following  table  gives  a  few  examples  of  American 
Straight  Dynamites,  but  it  must  be  borne  in  mind  that  the 
figures  are  only  average  ones  and  considerable  divergence  is 
often  met  with  : — 


Dynamice. 

70  per  cent. 

60  per  cent. 

50  per  cent. 

40  per  cent. 

30  per  cent. 

N.G.  .. 

7° 

60 

50 

40 

3° 

W.M. 

20 

I6'5 

T4 

12 

IO 

NaNO3 

7 

22-5 

35 

47 

59 

Na2CO3             ) 

MgC03 

3 

I 

I 

i 

i 

CaCo3               ) 

Of  these  40  per  cent.  Dynamite  is  probably  the  most 
used,  and  is  frequently  known  as  Hercules  Powder. 
T.  7 


Carbonite. 

Safety  Nitro. 

Stonite. 

•      25 

70 

68 

•      40-5 

12*6 

4 

•      34 

17-4 

— 

98  EXPLOSIVES 

Other  well-known  American  blasting  powders  of  this 
class  are — 

N.G 

W.M 

NaNOg  . . 

KNO3 8 

Guhr      ......     —  20 

Carbonate        . .         . .         '5 

An  explosive  of  this  class  much  used  in  South  Africa  is 
I,igdyn,  which  has  the  composition — 

N.G 40 

W.M.      ..          .+        13 

NaN03 45 

Wheat  flour      . .         . .         . .          . .  2 

As  will  be  seen,  it  is  very  similar  in  composition  to  the 
American  40  per  cent.  Dynamite  or  Hercules  Powder. 
Similar  mixtures  are  also  used  in  the  United  States  in 
which  about  half  the  nitroglycerine  has  been  replaced  by 
ammonium  nitrate.  These  are  known  as  Ammonia  Dyna- 
mites, and  are  made  in  several  grades,  40  per  cent.  Ammonia 
Dynamite,  for  example,  containing  about  20  per  cent,  of 
nitroglycerine  and  the  same  amount  of  ammonium  nitrate, 
the  balance  being  made  up  of  sodium  nitrate  and  wood  meal. 

Another  favourite  type  of  explosive  used  in  America  is 
a  kind  of  crude  gunpowder  to  which  nitroglycerine  has  been 
added.  The  gunpowder  base  is  composed  of  sulphur  and 
sodium  nitrate,  and  powdered  coal  is  frequently  substituted 
for  charcoal.  In  some  cases  wood  meal  is  added  to  assist 
the  absorption  of  the  nitroglycerine.  The  following  are 
typical  examples  of  this  class  of  explosive  : — 


N.G. 

NaN03  . . 

S     .. 

Charcoal  . . 

Coal  ....     15  20  18 

W.M.  ....     —  5 


Judson 

Vulcan 

Stump 

Low 

Powder. 

Powder. 

Powder. 

Powder. 

5 

30 

20 

5 

64 

52*5 

50 

70 

16 

7 

5 

7 

— 

10 

— 

— 

BLASTING  EXPLOSIVES 


99 


GELATINIZED  EXPLOSIVES 

In  1875  Nobel  discovered  that  collodion  cotton  was 
capable  of  dissolving  in  nitroglycerine  to  form  a  jelly.  This 
discovery,  which  was  of  an  accidental  nature  and  due  to 
Nobel  having  cut  his  finger  and  closed  the  wound  with 
collodion  prior  to  his  carrying  out  some  experiments  with 
nitroglycerine,  has  had  a  very  far-reaching  effect  on  the 
explosives  industry,  as  it  must  be  regarded  not  only  as  the 
forerunner  of  all  gelatinized  blasting  explosives,  but  also  of 
the  nitroglycerine  propellants. 

Gelatinized  explosives  have  several  great  advantages 
over  Dynamite.  In  the  first  place  they  dispense  with  all 
inert  ingredients,  so  that  the  whole  of  the  explosive  is  of  an 
active  nature.  Hence  much  more  powerful  explosives  can 
be  obtained,  but  at  the  same  time  these  are  easier  to  dope 
down  by  the  addition  of  wood  meal  and  nitrates.  The 
jellies  are  far  less  sensitive  to  moisture  than  Dynamite 
and  can  remain  in  contact  with  water  for  a  reasonable 
time  without  the  nitroglycerine  being  displaced,  and  at 
the  same  time  they  are  less  sensitive  to  shock.  The  labour 
involved  in  making  them  up  into  cartridges  is  much  less 
than  is  the  case  with  Dynamite  and  is  also  much  safer,  as 
the  somewhat  dangerous  dynamite  pump  is  not  required. 

Up  to  the  present  all  gelatinized  explosives  have  con- 
tained nitroglycerine,  but  jellies  can  also  be  obtained  by 
warming  collodion  cotton  with  certain  nitroaromatic  hydro- 
carbons such  as  the  so-called  liquid  trinitrotoluol.  Un- 
fortunately these  jellies  are  very  difficult  to  detonate  and 
are  not  very  stiff,  and  so  have  not  as  yet  found  any  applica- 
tion. Future  research,  however,  may  enable  these  dis- 
advantages to  be  overcome  and  thus  render  possible  a 
gelatinous  explosive  containing  no  nitroglycerine. 

In  manufacturing  gelatinous  explosives  the  dry  collodion 
cotton  is  weighed  out  into  bags  and  carried  to  the  nitro- 
glycerine department,  where  the  requisite  quantity  of 
nitroglycerine  is  measured  out,  poured  on  to  the  collodion, 


100 


EXPLOSIVES 


and  the  whole  mixed  by  hand.  The  thin  liquid  is  then 
carried  in  gutta-percha  buckets  with  light  wooden  lids  to 
the  mixing  house,  where  it  is  transferred  to  water-jacketed 
lead  tanks.  The  water  in  the  jacket  is  kept  at  about  50°  C., 
but  the  temperature  of  the  explosive  should  not  exceed 
40°-45°  C.  Gelatinization  is  allowed  to  proceed  for  some 
hours,  usually  overnight,  and  the  charge  then  transferred 
to  a  mixing  machine  and  mixed  mechanically  for  an  hour, 
any  dope,  such  as  wood  meal  and  potassium  nitrate,  being 
added  at  this  point.  The  machines  are  best  jacketed  with 
warm  water  to  prevent  the  jelly  becoming  too  stiff,  and  are 
usualty  of  the  Werner  and  Pfleiderer  type  shown  in  Fig.  15, 


FIG.  17. — McRoberts  Type  Incorporating  Machine  (Plan). 

p.  75.  To  avoid  all  chance  of  nitroglycerine  entering  the 
bearings,  however,  the  McRoberts  mixer,  shown  diagramma- 
tically  in  Figs.  17  and  18,  is  sometimes  preferred.  In  this 
case  the  explosive  mixing  pan  is  carried  on  a  platform  that 
can  be  lowered  so  that  the  mixing  arms  clear  the  top  of  the 
pan  and  allow  it  to  be  withdrawn.  In  charging  the  machine 
the  pan  is  withdrawn  and  the  jelly  loaded  into  it,  after 
which  it  is  wheeled  into  place  and  the  platform  raised. 
Stops  are  provided  to  prevent  the  pan  being  raised  too  high 
and  consequently  the  revolving  arms  coming  in  contact 
with  the  bottom.  Opinions  differ  as  regards  the  merits 
of  the  two  types  of  machine,  but  the  Werner  and  Pfleiderer 
type  is  usually  preferred  and  would  seem  to  cause  no  more 


BLASTING 


10 1 


accidents  than  the  McRoberts  type.  They  are  specially 
built  for  the  purpose,  and  precautions  are  taken  to  guard 
against  explosive  entering  the  bearings.  The  McRoberts 
machines  have  the  advantage  that  the  whole  process  of 
gelatinization  and  incorporation  can  be  carried  out  in  the 
same  tank,  thus  avoiding  transferring  the  jelly  from  the  gela- 
tinization tank  to  the  incorporating  machine ;  but,  on  the 
other  hand,  having  to  move  a  heavy  article  like  the  mixing 


U 


FIG.  1 8. — McRoberts  Type  Incorporating  Machine 
(Sectional  Elevation). 

tank  is  decidedly  objectionable.  When  incorporation  is 
complete  the  jelly  is  transferred  to  wooden  boxes  and  carried 
to  the  cartridge  huts,  where  it  is  put  through  "  sausage  " 
machines  and  the  resulting  cord  cut  up  with  double-bladed 
brass  knives  and  then  wrapped  in  parchment  paper. 

These  "  sausage  "  machines  (Figs.  19  and  20)  are  con- 
structed of  gun-metal  in  such  a  way  that  all  bearings  are 
external  so  that  no  explosive  can  get  into  them,  and  sufficient 
clearance  is  left  where  the  shaft  enters  to  avoid  friction. 


lo: 


EXPLOSIVES 


They  are  provided  with  internal  ribs  to  prevent  the  jelly 
from  merely  being  revolved,  and  are  always  worked  by  hand. 
The  conical  type  (Fig.  19)  was  the  original  type  used,  but 
the  circular  type  (Fig.  20)  is  now  generally  preferred,  as  it 
puts  less  pressure  on  the  explosive.  In  making  the  usual 
size  of  cartridge,  viz.  f  in.  or  }  in.,  two  nozzles  are  used  except 


FIG.  19. — Sausage  Machine  for  Gelatinized  Explosives. 

in  the  case  of  very  stiff  jellies  such  as  Blasting  Gelatine, 
when  only  one  is  used. 

Gelatinized   explosives,    like    all   explosives   containing 
nitroglycerine,  have  a  great  tendency  to  freeze,  and  in  this 


FIG.  20. — Sausage  Machine  for  Gelatinized  Explosives. 

condition  are  difficult  to  detonate.  Many  accidents  have 
been  caused  by  frozen  explosives,  as  some  of  the  cartridges 
in  the  shot  hole  may  escape  detonation  and  remain  mixed 
with  the  mineral  brought  down.  Also  it  is  difficult  to 
persuade  miners  to  thaw  frozen  explosives  in  a  warming 
pan,  so  that  many  fatalities  have  occurred  through  their 
being  thawed  over  a  fire  or  by  other  improper  means.  labo- 
ratory experiments  point  to  frozen  explosives  being  less 


BLASTING  EXPLOSIVES  103 

sensitive  to  shock  than  unfrozen  ones,  but  these  experi- 
ments are  quite  misleading  owing  to  the  small  quantities 
used.  Experience  under  working  conditions  shows  most 
decidedly  that  in  the  frozen  state  they  are  more  sensitive, 
and  not  a  few  accidents  have  been  caused  through  miners 
trying  to  make  a  hole  in  a  frozen  cartridge  in  which  to 
insert  a  detonator. 

For  this  reason  many  attempts  have  been  made  to  add 
substances  to  the  nitroglycerine  which  will  lower  its  freezing- 
point  sufficiently  to  allow  it  to  remain  liquid  at  ordinary 
working  temperatures.  The  freezing-point  coefficient  of 
nitroglycerine  is  70-5,  but  Raoult's  law  only  holds  good  for 
very  dilute  solutions,  and  these  are  of  but  little  value  from 
a  technical  point  of  view. 

Non-freezing  explosives  were  originally  made  by  adding 
nitrobenzole  or  nitrotoluol  to  the  nitroglycerine,  but  un- 
fortunately these  greatly  decrease  the  power  and  render 
detonation  more  difficult.  At  present  trinitrotoluol  is 
generally  used  and  is  frequently  applied  in  the  form  of  the 
so-called  liquid  T.N.T.,  as  this  mixes  more  readily  with  the 
nitroglycerine  than  solid  T.N.T. 

In  Great  Britain,  where  very  low  temperatures  are  not 
encountered,  the  amount  used  is  5-10  per  cent,  of  the  weight 
of  nitroglycerine,  but  in  America  and  on  the  Continent 
20-25  per  cent,  is  frequently  used. 

In  Germany  explosives  are  made  with  a  mixture  of 
nitroglycerine  and  dinitroglycerine,  tetranitrodiglycerine  or 
dinitrochlorhydrin,  and  in  France  dinitroglycol  is  used.  As 
would  be  expected  from  their  lower  molecular  weight,  these 
are  more  effective  than  nitroaromatic  hydrocarbons. 
Unfortunately  the  majority  of  suitable  substances  with 
low  molecular  weight  are  too  volatile,  but  nitromethane 
(B.P.  101°  C.)  has  been  proposed,  as  10  per  cent,  reduces 
the  freezing-point  of  nitroglycerine  to  —15°  C.  Its  cost, 
however,  is  against  its  use  at  present. 

Dinitroacetyl  glycerine  and  dinitroformin  (D.R.P. 
209,943)  have  also  been  proposed.  The  latter  is  very 
easily  made  by  heating  glycerine  with  half  its  weight  of 


104  EXPLOSIVES 

oxalic  acid  to  100°  C.  and  finally  to  150°  C.,  and  then  nitrating 
the  product.  The  oil  thus  obtained  contains  33  per  cent, 
of  dinitroformin  dissolved  in  nitroglycerine  and  is  almost 
unfreezable. 

The  three  standard  gelatinized  explosives  in  use  in  Great 
Britain  are  Blasting  Gelatine,  Gelatine  Dynamite,  and 
Gelignite,  the  average  composition  of  which  is  shown  in 
the  following  table  : — 

N.G.       C.C.      W.M.     KN03. 

Blasting  Gelatine  . .  92        8 

Gelatine  Dynamite  •  •     75        5          5        J5 

Gelignite     . .         . .         . .     60        4          8        28 

Of  these  Gelignite  is  far  the  most  used,  and  may  in  fact 
be  regarded  as  the  standard  high  explosive. 

Blasting  Gelatine,  which  forms  a  stiff  translucent  jelly, 
is  too  brisant  for  most  purposes,  although  used  for  hard 
rock.  It  is  the  most  powerful  explosive  on  the  market, 
but  has  several  serious  drawbacks.  In  the  first  place  it 
hardens  on  keeping,  and  at  the  same  time  becomes  very 
insensitive  so  that  it  can  only  be  exploded  by  means  of  an 
extra  heavy  detonator.  It  also  has  a  great  tendency  to 
sweat  or  exude  nitroglycerine,  especially  if  it  has  been 
frozen  and  thawed  several  times.  The  sweating  is  some- 
times quite  excessive,  and  the  nitroglycerine  may  actually 
be  seen  running  out  of  the  cases.  Needless  to  say  such 
Blasting  Gelatine  is  very  dangerous.  The  exudation  trouble 
is  very  noticeable  with  explosive  that  has  been  exported 
to  the  antipodes,  and  is  probably  accentuated  by  the  passage 
through  the  tropics,  hundreds  of  tons  being  condemned 
every  year  in  Australia  on  account  of  exudation.  It  is 
very  difficult  to  obtain  a  good  Blasting  Gelatine  that  will 
not  sweat  and  probably  most  depends  on  the  quality  of 
collodion  used.  This  should  contain  about  12  per  cent, 
of  nitrogen,  should  have  been  nitrated  at  a  low  temperature 
and  only  washed  in  hot  water  and  not  boiled.  Finally,  it 
should  not  have  been  over-pulped  as  this,  like  boiling, 
adversely  affects  its  gelatinizing  powers.  Other  gelatinized 
explosives  such  as  Gelatine  Dynamite  and  Gelignite  also 


BLASTING  EXPLOSIVES 


105 


have  a  tendency  to  sweat,  but  these  give  little  trouble  as 
the  wood  meal  holds  back  the  nitroglycerine. 

Since  1914,  when  the  outbreak  of  war  made  potash 
supplies  scarce,  Gelatine  Dynamite  and  Gelignite  have  been 
made  with  sodium  nitrate  in  place  of  the  potassium  salt. 

Nitroglycerine  is  slightly  gelatinized  when  used  for  a 
large  number  of  explosives,  as  by  thickening  it  without 
actually  forming  a  jelly  its  tendency  to  be  displaced  by 
water  is  lessened. 

In  the  United  States  many  grades  of  Gelatin  or  Gelatin 
Dynamite  are  manufactured,  in  some  of  which  the  wood 
meal  is  partly  replaced  by  flour  and  sulphur.  They  usually 
contain  one  per  cent,  of  calcium  carbonate,  and  have  a 
nitroglycerine  content  of  from  20  to  60  per  cent. 

In  France  gelatinized  explosives  are  known  as  Gommes, 
Dynamites  Gelatines,  or  simply  Gelatinees,  and  are  manu- 
factured in  great  variety,  both  potassium  and  sodium 
nitrate  being  used.  The  following  table  shows  a  few  typical 
examples  : — 


N.G. 

C.C. 

KN03 

NaNO3 

W.M. 

Gomme  extraforte 

92 

8 

_. 

_ 



Gomme  B  .  . 

86 

5 

4 

— 

5 

Gomme  G  .  . 

83 

5 

IO 

2 

Gomme  ^B 

74 

6 

*5'5 

.  —  - 

4  '5 

Gelatinee  iB 

64 

3 

24 

8 

Gelignite    .  . 

60 

3 

27 

10 

D)^namite  Gelatinee  2C 

43 

2 

4* 

—  " 

4 

Dynamite  No.  4  and  Dynamite  No.  5  are  both  jellies 
containing  sodium  nitrate,  the  former  containing  59  and 
the  latter  48  per  cent,  of  nitroglycerine. 

The  Belgian  Forcites  are  very  similar  in  nature  : — 


N.G. 

C.C. 

KN03 

NaNOg 

W.M. 

MgCOg 

Forcite  extra 

74 

6 

14 

__ 

5 

I 

Forcite  superieure 
Forcite  No.  i 

64 
49 

3 

2 

24 
3^ 

8 
13 

I 

Some  Belgian  Forcites  also  contain  ammonium  nitrate. 


106  EXPLOSIVES 

CHLORATE  AND  PERCHLORATE  MIXTURES 

The  formation  of  chlorates  from  the  metallic  chloride 
and  oxygen  is  an  endothermic  reaction,  and  consequently 
chlorates  in  themselves  are  capable  of  explosion — 

KC1  +  30  =  KC1O3  -  ii  -9.  Cal. 
NaCl  +  30  =  NaC103  -  13-1  Cal. 
BaCl2  +  60  =  Ba(C103)2  -  25-9  Cal. 

The  explosion  of  a  chlorate  is  brought  about  by  heat, 
or  by  heat  in  conjunction  with  shock,  and  although  the 
explosion  is  usually  not  violent  several  serious  accidents 
have  occurred.  The  instability  of  chlorates  renders  chlorate 
mixtures  very  sensitive,  and  in  most  countries  the  use  of 
chlorates  in  conjunction  with  sulphur  is  prohibited.  In 
Great  Britain  the  only  form  of  chlorate  explosive  that  is 
authorized  is  Cheddite,  the  chlorate  in  this  case  being  pro- 
tected and  rendered  less  sensitive  by  oil.  In  other  countries, 
however,  Sprengel  explosives  are  permitted,  in  which  the 
chlorate  and  the  combustible  matter  are  only  brought  in 
contact  with  one  another  immediately  before  charging  the 
bore  hole.  Chlorates  must  never  be  used  in  conjunction 
with  ammonium  salts,  such  as  ammonium  nitrate,  as  under 
these  conditions  double  decomposition  is  liable  to  take  place 
with  the  production  of  the  highly  unstable  ammonium 
chlorate,  a  salt  liable  to  spontaneous  explosion — 

KC103  +  AmN03  =  KNO3  +  AmClO3 

Perchlorates,  on  the  other  hand,  are  much  more  stable 
than  chlorates,  as  their  formation  from  the  chloride  and 
oxygen  is  an  exothermic  reaction — 

KC1  +  40  =  KC104  +7-9  Cal. 
NaCl  +  40  =  NaClO4  +  2-4  Cal. 
BaCl2  +  80  -  Ba(C104)2  +  4-3  Cal. 

Ammonium  perchlorate  is  also  stable,  but  is  capable  of 
explosion  although  only  with  difficulty.  Its  detonation  is 
represented  by  the  equation — 

NH4C1O4  =  C1+O2  +  N  +  2H2O  (gaseous)  +  38-3  Cal. 


BLASTING  EXPLOSIVES  107 

It  is  about  as  sensitive  to  blows  as  picric  acid,  but  the 
explosion  does  not  usually  spread  throughout  the  mass. 

Chlorates  are  invariably  manufactured  by  the  electrolysis 
of  chlorides,  and  on  further  electrolysis  pass  intoperchlorates. 
For  this  reason  commercial  perchlorates  are  liable  to  be 
contaminated  with  chlorate,  and  such  contamination  renders 
them  quite  unsuitable  for  use  in  the  manufacture  of  explo- 
sives. This  is  particularly  so  in  the  case  of  ammonium 
perchlorate,  as  the  presence  of  sodium  or  potassium  chlorate 
would  render  the  product  liable  to  double  decomposition 
with  the  production  of  ammonium  chlorate. 

Of  the  chlorates  the  potassium  salt  is  the  most  used,  as 
the  sodium  salt  is  very  soluble  and  deliquescent  and  con- 
sequently difficult  to  obtain  pure.  The  latter,  however, 
enters  into  the  composition  of  some  French  Cheddites,  and 
barium  chlorate  is  used  to  some  extent  as  an  ingredient  in 
fireworks.  Of  the  perchlorates  the  almost  insoluble  potassium 
salt  is  most  used,  although  the  ammonium  salt  can  be  obtained 
pure  at  a  reasonable  price.*  This  latter  salt  has  scarcely 
received  the  attention  it  deserves  in  this  country,  but  now 
that  it  has  been  manufactured  for  war  purposes  it  will 
probably  receive  greater  attention.  It  has  the  advantage 
of  giving  only  gaseous  products,  but  unfortunately  these 
include  chlorine.  Chlorine  fume  can  be  prevented  by  adding 
alkali  nitrate  in  sufficient  quantity  to  provide  a  base  to 
combine  with  the  chlorine  but  such  mixtures  are  liable  to 
deliquesce  owing  to  the  formation  of  ammonium  nitrate 
and  alkali  perchlorate  by  double  decomposition. 
AmC104  +  KN03  =  KC1O4  +  AmNO3 

For  Permitted  Explosives,  however,  the  base  might  be 
added  in  the  form  of  an  oxalate,  this  acting  at  the  same 
time  as  the  "  cooler,"  or  the  base  might  be  added  in  the 
form  of  a  salt  of  a  suitable  organic  acid,  the  organic 
part  of  the  molecule  providing  the  requisite  combustible 
matter. 

*  In  1918  the  cost  of  manufacture  of  ammonium  perchlorate  was  £99 
per  ton  as  compared  with  ^45  per  ton  for  ammonium  nitrate  (C.T.J., 
1919,  p.  162). 


108  EXPLOSIVES 

Sprengel  Explosives. — These  consist  of  cartridges  of 
potassium  chlorate,  which  immediately  before  use  are  dipped 
into  a  liquid  combustible.  They  are  not  authorized  in  Great 
Britain,  as  the  process  of  dipping  is  a  manufacturing  opera- 
tion within  the  meaning  of  the  Act  and  can  therefore  only  be 
carried  out  on  licensed  premises  and  under  "  danger  "  con- 
ditions. These  explosives  are  used,  however,  to  a  consider- 
able extent  on  the  Continent  and  in  America,  but  have  the 
disadvantage  that  the  penetration  of  the  combustible  liquid 
is  very  uneven,  so  that  uncertain  results  are  obtained.  In 
France  "  Explosif  63  "  or  "  Promethee  "  is  much  used,  and 
consists  of  cartridges  containing  80,  90  or  95  per  cent,  of 
potassium  chlorate  mixed  with  20,  10  or  5  per  cent,  of 
manganese  dioxide,  and  dipped  into  a  mixture  containing 
50  per  cent,  of  nitrobenzole  and  50  per  cent,  of  turpentine 
or  naphtha,  or  a  mixture  of  these.  The  American  explosive, 
Rack- a- Rock,  is  very  similar. 

lyiquid  air  explosives,  "Oxyliquits,"  may  be  mentioned 
at  this  point  as  they  are  of  the  Sprengel  type  although  con- 
taining no  chlorate.  They  consist  of  a  solid  organic  absorbent 
such  as  cork  dust,  on  which  liquid  air  or  oxygen  is  poured  just 
before  use.  They  were  used  in  the  construction  of  the  Simplon 
tunnel,  and  are  said  to  have  been  widely  used  in  Germany 
for  general  blasting  purposes  during  the  war,  but  are  not 
likely  to  come  into  general  use,  as  liquid  air  has  obvious 
disadvantages  and  inconveniences.  Also  the  density  of  the 
explosive  is  low  so  that  the  cost  of  making  bore  holes  is 
excessive.  lyiquid  air,  however,  is  cheap,  especially  where 
extensive  mining  operations  are  in  progress  and  large 
quantities  of  explosive  required.  The  great  advantage  of 
liquid  air  explosives  lies,  perhaps,  in  the  absence  of  danger 
from  misfires  or  incomplete  detonation.  With  ordinary 
explosives  accidents  due  to  misfires  necessitating  the  with- 
drawing of  the  charge  or  insertion  of  a  new  detonator  are 
not  uncommon,  and  incomplete  detonation  in  which 
cartridges  or  parts  of  cartridges  remain  in  the  debris  are 
apt  to  lead  to  accidents  through  being  struck  with  a 
pick  or  shovel.  With  liquid  air  explosives  these  dangers 


BLASTING  EXPLOSIVES  109 

do  not  exist,  as  the  air  rapidly  evaporates.  They  are 
not  authorized  in  Great  Britain,  for  the  same  reason 
that  chlorate  explosives  of  the  Sprengel  class  are  not 
authorized. 

Cheddites. — These  were  discovered  by  Street,  and 
derive  their  name  from  Chedde,  the  town  in  France  where 
chlorates  were  principally  manufactured.  They  consist 
usually  of  potassium  chlorate  mixed  with  a  fatty  oil,  usually 
castor  oil,  which  has  been  thickened  by  dissolving  aromatic 
nitro-compounds  in  it,  although  some  French  Cheddites 
are  made  with  paraffin.  As  nitro-compounds  a  mixture  of 
mononitronaphthalene  and  dinitrotoluol  is  generally  used, 
and  although  the  original  Cheddite  contained  2  per  cent, 
of  picric  acid  this  was  soon  replaced  by  dinitrotoluol.  In 
their  manufacture  the  nitro-compounds  are  first  dissolved 
in  the  oil  at  a  temperature  of  70°  C.  and  the  finely  ground 
dry  chlorate  added  slowly.  The  whole  is  well  mixed  by 
hand,  first  hot  and  then  in  a  semi-cold  condition,  sifted  and 
then  compressed  into  cartridges  in  wooden  moulds.  In 
order  to  obtain  a  satisfactory  explosive  the  degree  of  com- 
pression must  be  carefully  controlled,  especially  as  Cheddites 
are  usually  rather  easily  compressed.  If  the  density  is  too 
low  full  power  is  not  developed,  whereas  if  too  high  detona- 
tion becomes  difficult  or  impossible.  For  this  reason  con- 
siderable care  is  required  in  making  up  the  cartridges,  as 
some  Cheddites  are  very  readily  compressed,  especially 
those  made  with  sodium  chlorate.  The  following  table 
shows  the  velocity  of  detonation  of  three  different  Cheddites 
at  different  densities,  the  experiments  being  carried  out  in 
copper  tubes  22  mm.  in  diameter.  The  explosives  used  had 
the  composition — 

Type  6o4.          P.  S. 

KC103        ....  75            90 

NaClO3      ....  89 

•M.N.N.       ..          ..  i 

D.N.T 15 

Paraffin  —             10             n 


no 


EXPLOSIVES 


Temperature. 


3°-4° 


TYPE  6o4 

Density. 

•81 

i '39 
1-48 

1-62 
EXPI,OSIF  P 


Temperature. 


3°C. 


15°  C. 


Temperature. 


17°  C. 


EXPI,OSIF  S 

Density. 

•81 

•92 

i'45 
1-56 


Velocity. 
Metres  per  sec. 

2457 
3045 
3156 

3099 
2820 


Velocity. 
Metres  per  sec. 

2137 
3044 
3185 
3621 

3475 
Incomplete 

2940 

3457 

3565 

Incomplete 


Velocity. 
Metres  per  sec. 

2191 

2475 
2966 
2940 
2688 
Incomplete 


The  density  acquired  by  the  same  explosives  under 
different  pressures  is  shown  in  the  following  table,  the 
pressure  being  given  in  kilograms  per  cm.2  :— 


Type  6o4. 

Explosif  P. 

Explosif  S. 

Pressure. 

Density. 

Pressure. 

Density. 

Pressure. 

Density. 

'7 

1-25 

*7 

•9 

•02 

•92 

1*4 

1-31 

1*6 

'99 

§3 

1*29 

1-6 

I-38 

5'9 

I'2I 

•6 

1*33 

2-1 

I  '40 

8-0 

1-29 

'7 

1*39 

3-2 

1*46 

2O'O 

1*37 

*'4 

1-47 

4-8 

1*5* 

58'0 

i'59 

3-2 

i'55 

BLASTING  EXPLOSIVES 


in 


The  following  table  shows  the  composition  of  the  chief 
French  Cheddites  :— 


KC103. 

NaCI03. 

Castor  oil. 

M.N.N. 

D.N.T. 

Paraffin. 

Fype  60 

80 

__ 

6 

12 

2 



Fype  41 

80 

—  • 

8 

12 

—  • 

— 

D2 

79 

— 

5 

I 

15 

— 

34 

90 

—  • 

— 



—  • 

10 

_)g          •  • 

79 

5 

1 

16 

~ 

Of  these  O5  is  the  most  brisant  and  O3  the  least. 

Cheddites  are  also  authorized  and  used  in  Great  Britain, 
but  the  demand  is  not  great.  Thus  in  1910,  out  of  a  total 
consumption  of  15,000  tons  of  blasting  explosives  of  all 
classes,  only  60  tons  were  Cheddite. 

In  Germany  mixtures  of  chlorates  and  resin  are  used  to 
some  extent,  e.g.  Silesia  No.  4  consists  of  80  per  cent,  of 
potassium  chlorate  and  20  per  cent,  of  resin.  Some  years 
ago  attempts  were  made  to  introduce  similar  explosives 
into  Great  Britain  under  the  name  of  Steelite.  These  were 
composed  of  potassium  chlorate  and  resin  which  had  been 
previously  oxidized  by  nitric  acid.  They  never  came  into 
general  use,  although  Colliery  Steelite  was  on  the  old  "  Per- 
mitted "  list,  but  failed  at  the  Rotherham  test.  It  had  the 
composition — 


KC103    .. 
Oxidized  resin 
Castor  oil 
Moisture 


..    23-5-26-5 

0-1 


Perchlorates  have  been  suggested  as  a  substitute  for 
nitre  in  black  powder,  but  have  not  been  used  to  any  extent. 
A  British  explosive,  Polarite,  was  introduced  some  years 
ago  as  a  substitute  for  Gelignite  and  seemed  to  consist  of 
a  non-freezing  Gelignite  containing  T.N.T.  in  which  potassium 
perchlorate  was  used  in  place  of  nitre.  The  German  explo- 
sive, Permonite,  was  on  the  old  "  Permitted  "  list  in  Great 


H2  EXPLOSIVES 

Britain,  but  failed  to  pass  the  Rotherham  test.     It  had  the 
composition — 

KC104        31-34 

N.G 3-4 

C.C -5-1 

AmNO3 39-43 

T.N.T 11-13 

Starch        . .          . .          . .          . .  5-9 

W.M.  ^ 1-5-3-5 

Glycerine  ) 

Gelatine     (           ••          "          "  I'5-3'5 

The  French  Government  experimented  with  two  Cheddites 
made  with  ammonium  per  chlorate  and  having  composition — 

No.  i.  No.  2. 

AmClO4 82  50 

D.N.T 13  15 

NaNO3 —  30 

Castor  oil              . ,  5  5 

but  did  not  authorize  them  as  they  presented  no  advantages 
over  existing  Cheddites.  The  use  of  castor  oil,  however,  in 
the  presence  of  perchlorate  would  seem  useless  as,  unlike 
the  chlorates,  they  are  not  sensitive  to  friction. 

The  Belgian  Yonckites  are  ammonium  perchlorate  ex- 
plosives for  use  in  coal  mines,  and  consist  of  ammonium 
perchlorate  mixed  with  sodium  and  ammonium  nitrate, 
trinitrotoluol  and  sodium  chloride. 

The  Swedish  explosive,  Blastine,  is  composed  of  ammo- 
nium perchlorate,  sodium  nitrate,  D.N.T.  and  paraffin. 
Pernitral  was  the  name  of  an  explosive  authorized  in  this 
country  a  few  years  ago,  but  the  manufacture  of  which 
does  not  seem  to  have  been  taken  up.  It  had  the 
composition — 

AmClO4  40 

NaNO3 30 

Solid  T.N.T 10 

liquid  T.N.T 10 

Al  powder         . .          . .          . .          . .  10 


BLASTING  EXPLOSIVES  113 

Samples  tested  by  the  author  seemed  to  be  somewhat 
more  powerful  than  Blasting  Gelatine,  but  unfortunately  a 
No.  8  detonator  was  required  in  order  to  obtain  the  full 
effect. 

AMMONIUM  NITRATE  EXPLOSIVES 

Explosives  consisting  of  ammonium  nitrate  in  conjunc- 
tion with  combustible  matter,  a  nitroaromatic  hydrocarbon 
for  preference,  were  first  proposed  by  Favier  in  1885.  They 
have  the  advantage  of  being  cheap  and  safe  to  manufacture 
and  use,  but  have  the  serious  disadvantage  of  being  very 
hygroscopic,  so  that  even  when  put  up  in  carefully  waxed 
cartridges  they  take  up  moisture  rapidly  and  become  unfit 
for  use  in  a  few  weeks.  As  a  class  they  have  extremely 
low  temperatures  of  explosion,  and  for  this  reason  are  largely 
used  as  coal  mine  explosives  (see  Section  V.),  but  are  also 
used  to  some  extent  for  general  blasting  purposes.  Their 
use  for  general  purposes  is  likely  to  extend  in  the  near  future 
owing  to  the  low  price  at  which  they  can  be  manufactured. 
The  best-known  British  explosives  of  this  class  are  discussed 
in  the  next  section,  but  the  following  have  been  used  to  a 
considerable  extent  in  Germany — 

Astralit.  Fulmenit. 

AniNO3       81  82-5 

T.N.T ii  ii 

Paraffin  Oil            . .                  i  i 
Meal            . .          . .          . .       2 

Coal i 

N.G 4 

Charcoal      . .          . .          . .  1-5 

Guncotton —  4 

Westfalit  fur  Kohle. 

AmNO3         . .         . .  91 

KNO3            ..          ..  4 

Resin . .          . .          . .  5 

For  ordinary  blasting  purposes  it  has  been  proposed  to 
increase  the  power  of  ammonium  nitrate  explosives  by  the 
T.  8 


H4  EXPLOSIVES 

addition  of  aluminium  powder,  the  heat  of  combustion  of 
which  is  very  high — 

2A1  +  3O2  =  2A12O3  +  760  Cal. 

The  best  known  of  these  explosives  is  Ammonal,  which 
for  ordinary  blasting  purposes  contains  about  25  per  cent, 
of  aluminium  powder,  the  balance  being  ammonium  nitrate 
and  T.N.T.  Ammonals  containing  much  less  aluminium, 
however,  are  also  manufactured,  for  example — 

AmNO3         . .         . .  94  93  88        81 

Al 3  3  8        15 

C        3  44 

T.N.T —  4 

Gesteins-Westfalit  contains  dinitrotoluol,  and  has  the 
composition — 

AmNOg         84-5 

Al 3'5 

D.N.T 12-0 

In  all  explosives  of  this  nature  the  aluminium  is  added 
in  the  form  of  a  fine  powder,  but  too  fine  a  state  of  sub- 
division is  to  be  avoided,  as  very  finely  powdered  aluminium 
oxidizes  readily  in  the  air.  As  a  rule  the  commercial 
"  aluminium  bronze  "  is  used.  This  is  manufactured  by 
rolling  aluminium  into  very  thin  sheets,  which  are  then  cut 
into  strips  and  ground. 

Very  similar  explosives  in  which  calcium  silicide  is  used 
in  place  of  aluminium  are  also  manufactured,  Sabulite 
being  an  explosive  of  this  class.  The  use  of  ferrosilicon  has 
also  been  proposed  (A.P.  1,277,043),  although  it  does  not 
seem  to  have  come  into  use. 

In  making  up  ammonium  nitrate  explosives  into  cart- 
ridges two  methods  are  used.  If  loaded  by  hand  the  paper 
is  rolled  on  a  wooden  rod  of  suitable  size  and  one  end  folded 
in  and  closed.  The  paper  cylinder  thus  formed  is  then 
inserted  closed  end  downwards  in  an  aluminium  tube  fixed 
in  a  block  of  wood,  and  the  explosive  fed  in  through  an 
aluminium  funnel  and  well  rammed  with  a  wood  or  aluminium 


BLASTING  EXPLOSIVES 


rod.  This  method  has  little  to  recommend  it  except  that 
the  plant  can  be  bought  for  a  few  shillings.  A  much  more 
satisfactory  method  is  to  use  a  helix  machine  very  similar 
to  the  "  sausage  "  machines  used  for  gelatinized  explosives, 
the  machine  being  made  to  work  against  a  suitable  resistance 
in  order  to  pack  the  powder  evenly  and  firmly.  A  simple 
machine  of  this  nature  for  use  with  hand  power  is  shown  in 
Fig.  21.  The  explosive  is  fed  in  through  the  hopper  and  the 


FIG.  21. — Cartridge  Filling  Machine  for  Ammonium  Nitrate  Explosives. 

paper  cylinder  held  against  the  nozzle  by  means  of  a  cord 
and  weight.  As  the  loading  proceeds  the  paper  is  forced 
backwards  away  from  the  nozzle,  an  adjustable  stop  being 
provided  to  indicate  when  loading  is  complete.  By  varying 
the  weight  the  explosive  can  be  packed  more  or  less  tightly 
at  will.  In  Germany  similar  machines  are  used  that  are 
power-driven,  but  these  as  a  rule  are  vertical. 


TONITK 

This  was  formerly  much  used  for  blasting  purposes,  and 
consisted  of  compressed  guncotton  containing  from  25  to  40 
per  cent,  of  a  nitrate,  usually  barium  or  potassium  nitrate. 
Its  interest  is  now  chiefly  historical. 


LITERATURE 
DYNAMITE 

Two  interesting  accidents  which  have  occurred  in  the  manufacture  of 
Dynamite  are  described  in  StR.,  145,  184; 


Ii6  EXPLOSIVES 

GELATINIZED  EXPLOSIVES 

The  following  accounts  of  accidents  are  instructive:  S.R.,  151,  201. 
For  notes  on  the  exudation  of  nitroglycerine  from  Blasting  Gelatine, 
see  A.E.,  1914. 

CHLORATE  EXPLOSIVES 

Much  information  on  the  properties  of  Cheddites  will  be  found  in 
P.S.,  xi.,  22;  xii.,  123;  xiii.,  29,  144,  282;  xiv.,  26,  33,  192;  xv.,  135, 
212,  247  ;  xvi.,  66. 

Two  accidents  in  this  country  are  described  in  S.R.,  135  and  185. 

AMMONIUM  NITRATE  EXPLOSIVES 
E.P.  2139";   16,277°°;   A.P.  1,277,043. 

BLASTING 
O.  Guttmann,  "  Blasting,"  London,  1906. 


SECTION    V.— SAFETY    COAL    MINE 
EXPLOSIVES 

THE  use  of  explosives  in  coal  mines  is  always  attended  by 
the  risk  of  firing  the  mine  gases  and  coal  dust.  This  ignition 
may  be  due  to  some  extent  to  the  vibration  set  up  by  the 
shock  of  the  explosion,  but  the  greatest  risk  is  due  to  local 
rise  in  temperature  caused  by  the  flame  of  the  explosion  or 
by  the  adiabatic  compression  of  the  gas.  Air,  for  example, 
when  adiabatically  compressed  to  60  kg.  per  cm.2  suffers  a 
rise  in  temperature  of  670°  C.,  whereas  at  100  kg.  per  cm.2  it  is 
820°  C.,  and  at  200  kg.  per  cm.2  it  is  1060°  C.  A  mixture  of  air 
and  fire  damp  will  inflame  at  650°  C.,  but  at  this  temperature 
there  is  a  period  of  induction  of  about  10  seconds,  although 
this  period  grows  progressively  shorter  with  increasing 
temperature.  Under  working  conditions  in  a  mine  rapid 
diffusion  takes  place  so  that  although  locally  the  temperature 
may  rise  far  above  the  point  of  inflammation,  the  diffusion  of 
the  overheated  gases  cools  them  before  the  period  of  in- 
duction is  complete,  and  hence  no  explosion  results.  Of 
course,  there  is  a  limiting  temperature  above  which  the 
period  of  induction  is  so  short  that  inflammation  takes  place 
before  diffusion  has  had  time  to  lower  the  temperature  below 
the  ignition  point,  and  for  safety  it  is  consequently  necessary 
to  select  explosives  and  conditions  of  shot  firing  in  such  a 
way  that  the  local  rise  in  temperature  is  not  excessive. 
The  problem  is  a  difficult  one,  as  mine  conditions  are  very 
variable,  and  the  chief  danger  arises  from  abnormal  cases, 
such  as  blown-out  shots.  Consequently  the  tests  applied 
are  of  an  empirical  nature,  although  designed  as  far  as  possible 
to  represent  actual  working  conditions.  Usually  they 
imitate  what  might  happen  in  a  mine  under  the  worst  possible 
conditions. 

In  order  to  investigate  the  problem  and  lay  down  rules 


n8 


EXPLOSIVES 


for  blasting  in  gassy  mines,  almost  all  civilized  countries 
in  which  coal  mining  is  an  important  industry  have  appointed 
Commissions.  The  first  of  these  was  appointed  in  France 
in  1877,  the  British  Commission  being  appointed  two  years 
later,  and  the  Prussian  Commission  in  1881.  The  Belgian 
and  Austrian  Commissions  were  both  set  up  at  a  rather  later 
date.  The  result  of  these  Commissions  has  been  the  setting 
up  of  galleries  in  which  explosives  can  be  fired  into  a  gas 
mixture,  or  into  air  or  gas  laden  with  coal  dust,  and  the 
laying  down  of  regulations  limiting  the  composition  of  the 
explosives  which  may  be  used,  the  weight  that  may  be  used 
in  any  one  blast,  and  the  conditions  under  which  blasting 
may  be  carried  out. 


Explosive. 

Density. 

Velocity  of     Length  of     Duration  !     «**"" 
Detonation.      Flame.      of  Flame,  i     R^tio 

(KN03 

75 

G.P.                 C. 

12 

I-04 

200-300         i  10          77            1:330 

Is. 

13 

R  r                /N.G. 

B-G-           (c.c. 

92 
8 

I-63 

7700           224           9*72       i  :  883 

Dynamite     {Q  jjl 

75 
25 

1-58 

6818           228           8-31       1:620 

(N.G.* 

63|5 

i 

Ic.c. 

Gelignite       }NaNO3 

27 

I-67 

6210           150           1*23       i  :  101 

(W.M. 

8 

AmNO3 

80 

N.G. 

3'8 

Donarite 

C.C. 

'2 

I-3I 

3930             69             -40      1:15 

T.N.T. 

I2'O 

4137 

Flour 

4-0 

(confined) 

AmNO3 

80-3 

KN03 

5'° 

Ammon- 
Carbonite 

N.G. 
C.C. 

4-0 

•2 

I'll                 1753                   51                    '32 

1:7-4 

Coal 

Starch 

6-0 
4*5 

3*95 
(confined) 

AmNO3  92 

2137 

Thunderite 

T.N.T. 

4 

1-07        3654                      -33 

— 

Flour 

4 

(confined) 

i 

Bichel  has  investigated  the  duration  of  flame  by  firing 
explosives  at  night  and  photographing  the  flame  through  a 
quartz  lense  on  a  moving  film.  He  finds  that  in  all  cases  the 
flame  outlasts  the  time  of  detonation,  and  has  named  the 


SAFETY   COAL  MINE  EXPLOSIVES         119 


ratio  duration  of  detonation  :  duration  of  flame  the  "  after- 
flame  ratio."  He  finds  that  safety  explosives  have  a  very 
short  flame  duration,  and  consequently  a  high  after-flame 
ratio,  the  table  in  the  preceding  page  showing  some  of  his 
figures,  velocity  of  detonation  being  given  in  metres  per 
second,  duration  of  flame  in  thousandths  of  a  second  and 
length  of  flame  in  millimetres.  The  experiments  were  carried 
out  with  100  grams  of  explosives  made  up  in  cartridges  of 
30  mm.  diameter,  and  fired  from  a  gun  similar  to  those  used 
in  the  official  testing  galleries. 

In  the  American  testing  station  at  Pittsburg  several 
explosives  were  analyzed  and  the  flame  from  200  grams 
photographed,  and  the  heat  liberated  measured.  The 
following  very  interesting  figures  were  obtained.  The  heat 
liberated  is  expressed  in  major  calories  per  kilogram,  and 
the  duration  of  flame  in  milliseconds — 


Composition. 

Weight  of 
wrapper  per 
100  grams. 

Per  cent.  CO 
in  products 
of  Explosive. 

Heat              Duration 
liberated.         of  Flame. 

D.N.T. 

17-85    . 

; 

M.N.N. 

1*30   • 

l 

Castor  oil 

5*32    . 

5 

41 

1065       '196 

KC103 

75'36   . 

H20 

•17    . 

N.G. 

8-13    • 

M.N.T. 

3'57    • 

Castor  oil 

•81    . 

N.C. 

•56    • 

6'5 

5*9 

1169 

•279 

AmNO3 

82-11    . 

W.M. 

4-30   . 

H2O 

•52    - 

KN03 

65'3i    • 

C. 

19-52    • 

S. 

2-63   . 

None 

4° 

622*7             i°3° 

Paraffin 

3'  35    • 

Starch 

8-73   • 

This  last  explosive  would  appear  to  be  Bobbinite,  and 
in  view  of  its  great  flame  duration  it  is  scarcely  surprising 
that  it  does  not  pass  the  Rotherham  Test. 

Will  has  also  studied  the  duration  of  flame  by  photo- 
graphic methods.  He  took  his  photographs  on  a  drum 


120  EXPLOSIVES 

covered  with  a  sensitive  film  over  which  was  laid  an  opaque 
screen,  in  which  a  series  of  equidistant  slits  were  cut,  the 
whole  being  rapidly  rotated  behind  a  fixed  opening.  By 
this  means  he  obtained  a  species  of  cinematograph  photo- 
graphs in  the  form  of  a-  series  of  bands.  He  found  that  with 
explosives  deficient  in  oxygen  the  flame  dies  away  very 
rapidly  and  then  revives,  the  secondary  flame  being  of  much 
greater  duration  than  the  primary  flame.  This  secondary 
flame  is  due  to  the  carbon  monoxide  escaping  from  the  bore 
hole  and  burning  in  contact  with  atmospheric  oxygen,  and 
can  be  prevented  by  the  addition  of  a  few  per  cent,  of  an 
alkali  salt,  the  salts  of  the  alkali  metals  being  far  more 
effective  than  the  salts  of  the  alkali  earths  or  of  lead. 

The  first  proposal  for  rendering  explosives  used  in  fiery 
mines  safe  by  reducing  the  temperature  of  explosion  was  due 
to  MacNab,  who  in  1873  suggested  placing  a  cartridge  of 
water  immediately  above  the  charge  in  the  bore  hole.  This 
suggestion  was  soon  followed  by  others,  in  which  wet  moss 
or  a  jelly  containing  90  per  cent,  of  water  was  substituted  for 
the  inconvenient  cylinder  of  water,  but  none  of  these  met 
with  any  great  success,  partly  owing  to  the  tendency  of  the 
miners  to  omit  using  them,  and  partly  owing  to  the  contents 
being  blown  about  in  large  lumps,  and  not  being  sufficiently 
pulverized  by  the  explosion.  The  next  step  was  the  use  of 
salts  containing  water  of  crystallization,  such  as  magnesium 
sulphate,  as  these  could  be  incorporated  with  the  explosive 
itself,  and  this  method  is  still  used  to  a  slight  extent,  although 
almost  all  modern  safety  explosives  rely  on  the  chlorides  of 
sodium,  potassium  or  ammonium  as  "  coolers,"  the  cooling 
being  brought  about  by  the  heat  absorbed  by  the  volatiliza- 
tion, and  to  some  extent  also  by  the  dissociation  of  these 
salts.  Ammonium  chloride  has  the  disadvantage  that  it 
is  apt  to  spoil  the  detonation  of  the  explosive,  and  it  must  be 
used  in  conjunction  with  at  least  one  equivalent  of  an  alkali 
nitrate  to  provide  a  base  with  which  the  free  chlorine 
liberated  during  the  explosion  may  combine.  It  also 
renders  the  explosive  hygroscopic  as  double  decomposition 
takes  place  with  the  production  of  ammonium  nitrate — 


SAFETY   COAL  MINE  EXPLOSIVES        121 
KN03  +  NH4C1  =  KC1  +  NH4N03 

A  salt  containing  water  of  crystallization  when  used  in 
conjunction  with  ammonium  nitrate  is  also  objectionable, 
as  the  nitrate  is  apt  to  rob  it  of  its  water  and  to  become  liquid 
by  solution. 

In  Great  Britain  explosives  that  may  be  used  in  fiery 
mines  are  known  as  "  Permitted  Explosives/'  in  the  United 
States  as  "  Permissible  Explosives,"  in  France  as  "  Explosifs 
de  Surete,"  or  "  Explosifs  Anti-grisouteuses,"  in  Belgium  as 
"Explosifs  S.  G.  P."  ("Sure  Grisou  Poussieres  "),  and  in 
Germany  as  "  Wetter-  or  Wettersichere  Sprengstoffe." 

Test  Galleries. — The  German  gallery  is  at  Gelsenkirchen- 
Schalke,  and  is  35  metres  long.  It  is  elliptical  in  section,  and 
has  a  sectional  area  of  two  square  metres,  the  major  axis 
being  vertical  and  1*8  metres  long,  and  the  minor  axis 
i  "35  metres  long.  Shots  are  fired  into  an  explosion  chamber, 
formed  by  partitioning  off  a  length  of  5  metres  by  means  of 
a  paper  diaphragm,  from  a  gun  with  a  bore  4  cm.  in  diameter 
and  70  cm.  deep.  The  gun  is  inclined  at  a  slight  angle,  and 
the  shots  are  fired  without  any  stemming.  There  is  a 
statutory  obligation  for  owners  of  fiery  mines  to  use  only 
"  safe  explosives,"  but  it  rests  with  the  owner  to  decide  what 
explosive  is  safe.  Several  private  galleries  also  exist, 
notably  the  one  at  Neubabelsberg. 

The  Austrian  gallery  is  293  metres  long,  and  is  part  of 
an  abandoned  mine.  The  shots  are  fired  suspended  in  the 
mine,  and  not  from  a  gun,  thus  representing  more  or  less 
the  conditions  of  an  explosive  exploding  accidentally  before 
being  placed  in  the  shot  hole. 

The  Belgian  gallery  at  Frameries,  near  Mons,  is  similar 
to  the  German  gallery  described  above,  but  is  85  metres 
long.  The  shots  are  fired  unstemmed  from  a  gun  with  a 
bore  5*5  cm.  in  diameter  and  46  cm.  deep,  the  gun  being 
inclined  at  an  angle.  The  explosive  gas  used  is  air  containing 
8  per  cent,  of  fire  damp,  the  mixture  being  warmed  to 
25°  C.  The  power  of  the  explosive  is  determined  by  com- 
parison with  Dynamite  No.  i  in  the  Trauzl  lead  block,  and 


122  EXPLOSIVES 

in  order  to  pass  the  test  ten  shots  of  an  amount  equivalent 
to  175  grams  of  Dynamite  must  fail  to  fire  the  gas  mixture, 
and  also  fail  to  fire  coal  dust.  The  largest  charge  that  satis- 
fies these  conditions  is  the  "  charge  limite  "  or  the  maximum 
amount  of  that  explosive  that  may  be  used  in  any  one  blast. 

The  French  galleries  are  at  lyievin,  one  being  15  metres 
long  and  2  metres  in  area,  and  the  other  300  metres  long  and 
2  '8  metres  in  area,  both  being  of  circular  section  and  supplied 
with  natural  gas.  The  French  regulations,  however,  are 
not  based  on  experiment,  but  rather  on  theoretical  considera- 
tions. For  use  in  coal  mines  an  explosive  must  on  detonation 
yield  no  combustible  products  such  as  carbon  monoxide, 
and  for  use  in  rock  (explosif  roche)  its  calculated  temperature 
must  not  exceed  1900°  C.,  or  for  use  in  coal  (explosif  couche) 
1500°  C.  These  calculated  temperatures  are  based  on  the 
heat  of  combustion  of  the  constituents  and  on  the  specific 
heat  of  the  products  of  combustion,  and  further  details  will 
be  found  in  Section  VIII. 

The  United  States  gallery  is  situated  at  Pittsburg,  It  is 
100  ft.  long  by  6  ft.  4  in.  in  diameter,  and  is  constructed  of 
boiler  plate,  and  closed  at  one  end  by  concrete.  Safet}7  doors 
are  placed  along  the  top  to  prevent  undue  pressure  being 
developed.  Shelves  are  placed  along  the  sides  of  the 
gallery  to  hold  coal  dust,  this  dust  being  obtained  from 
bituminous  coal  ground  until  it  passes  a  loo-mesh  sieve. 

The  shots  are  fired  unstemmed  from  a  gun  24  in.  in 
diameter  and  36  in.  long,  with  a  bore  hole  2  J  in.  in  diameter 
and  21  J  in.  deep.  Natural  gas  (roughly  equal  parts  of 
methane  and  ethane)  is  used,  and  the  gas-air  mixture  is 
warmed  to  77°  F.  Power  is  determined  in  the  ballistic 
pendulum  (see  Section  VIII.)  and  is  compared  with  American 
40  per  cent.  Straight  Dynamite  of  the  composition  — 

N.G  .......  40 

NaNO3     ......  44 

W.M  .......  15 

......  i 


In  order  to  pass  the  test  and  be  placed  on  the  list  of 


SAFETY  COAL   MINE   EXPLOSIVES         123 

"  Permissible   Explosives/'    an   explosive    must   fulfil   the 
following  conditions : — 

1.  Ten  shots  of  a  weight  equivalent  to   |  Ib.  of  the 
standard  40  per  cent.  Dynamite  fired  into  8  per  cent,  of  gas 
must  cause  no  explosion. 

2.  Ten  shots  of  the  same  weight  fired  into  4  per  cent,  of 
gas  with  the  addition  of  20  Ibs.  of  coal  dust  must  cause  no 
explosion. 

3.  Ten  shots  of  the  same  weight  fired  into  40  Ibs.  of  coal 
dust  must  cause  no  explosion. 

The  limit-charge  is  determined  by  firing  amounts  in- 
creasing by  25  grams  into  4  per  cent,  of  gas  and  20  Ibs.  of 
coal  dust  until  the  maximum  amount  is  found  of  which 
10  shots  can  be  fired  without  causing  an  explosion.  The 
composition  of  explosive  is  not  published. 

The  first  British  gallery  was  built  at  Woolwich,  and  was 
only  27  ft.  6  in.  long  by  2  ft.  6  in.  diameter.  The  explosives 
were  fired  from  a  gun  with  a  bore  hole  30  in.  deep  and  if  in. 
diameter,  and  were  stemmed  with  a  definite  weight  of  dry 
clay.  The  explosive  mixture  used  was  air  containing  15  per 
cent,  of  coal  gas.  This  gallery  has  been  abandoned  since 
1912,  in  which  year  the  Rotherham  gallery  came  into  use. 
This  is  50  ft.  long  by  5  ft.  in  diameter,  and  is  constructed 
of  J  in.  mild  steel  plate.  The  explosion  chamber  is  18  ft. 
long,  and  is  separated  from  the  rest  of  the  gallery  by  a  paper 
diaphragm.  The  outer  end  is  closed  by  a  |-in.  steel  plate,  a 
hole  being  provided  for  inserting  the  gun  and  arrangements 
made  for  a  gas-tight  joint.  The  explosion  chamber  has 
three  windows  made  of  f-in.  plate  glass,  each  being  6  in. 
square.  There  are  nine  pressure  release  valves  on  the  top. 

The  gas  is  measured  in  a  gas  holder,  and  then  made  to 
circulate  with  the  air  in  the  explosion  chamber  by  means  of 
fans,  complete  mixing  being  brought  about  in  3  minutes. 
The  mixture  used  contains  13*4  per  cent,  of  gas. 

The  gun  is  of  steel  (wire  construction),  with  a  bore  hole 
55  mm.  in  diameter  and  120  cm.  deep. 

The  following  are  the  conditions  regulating  the  test  as 
abstracted  from  A.R.  1912  : — 


124  EXPLOSIVES 

The  explosive  must  be  on  the  L,ist  of  Authorized  Ex- 
plosives. The  Secretary  of  State  may  at  any  time  cause 
any  explosive  on  the  Permitted  Ijst  to  be  formally  retested. 
Notice  of  any  such  formal  retest  will  be  sent  to  the  manu- 
facturer of  the  explosive. 

For  the  test  the  following  weights  and  sizes  of  cartridges 
must  be  supplied  : — 

33  Ibs.  if"  x  8  oz. 
10  Ibs.  if"  x  4  oz. 

5  Ibs.  if"  x  2  oz. 

2  Ibs.  if"  x  4  oz. 

The  Secretary  of  State  reserves  to  himself  the  right  of 
storing  all  explosives  submitted  for  the  Official  Test  for  at 
least  30  days  prior  to  the  test. 

The  fees  for  testing  an  explosive  are  : — 

Testing  a  new  explosive  . .          .  .          . .     £50 

Testing  an  altered  explosive    . .          . .          . .     £30 

Bach  experimental  shot  . .          . .          .  .     £i 

These  experimental  shots  have  no  official  significance,  but 
are  for  the  benefit  of  manufacturers  in  order  to  enable  them 
to  form  some  idea  as  to  whether  an  explosive  is  likely  to  pass 
or  not  before  paying  the  somewhat  heavy  fee  for  the  Official 
Test. 

The  Official  Test  is  carried  out  as  follows  (official  descrip- 
tion) : — 

"  Shots  will  be  fired  into  a  mixture  of  gas  and  air  until 
the  largest  charge  which  can  be  fired  without  igniting  it  is 
found.  Further  shots  will  then  be  fired,  beginning  with  this 
charge  and,  in  the  event  of  an  ignition,  reducing  the  charge— 
until  five  shots  of  the  same  weight  have  been  fired  without 
igniting  the  mixture.  Shots  will  then  be  fired  with  the 
charge  so  determined  into  coal  dust,  and  the  same  procedure 
adopted  until  5  shots  have  been  fired  without  igniting  the 
coal  dust.  The  lower  of  the  charges  thus  determined  will 
be  known  as  the  '  maximum  charge/  In  making  alterations 


SAFETY   COAL  MINE  EXPLOSIVES        125 

to  the  weight  of  the  charges,  the  increment  or  decrement 
of  charge  will  not  be  less  than  two  ounces." 

"  In  loading  the  gun  the  charge  will  be  pushed  to  the 
bottom  of  the  bore  (a  clay  plug  having  been  previously 
inserted  to  protect  the  crown  of  the  bore),  and  will  have  no 
tamping.  The  coal  dust  will  be  ground  to  such  a  degree  of 
fineness  that  not  less  than  90  per  cent,  will  pass  through  a 
sieve  of  150  meshes  to  the  linear  inch." 

"  In  addition  to  the  foregoing  shots,  other  shots  will  be 
fired  at  the  ballistic  pendulum,  and  the  swings  registered  on 
the  sliding  scale  provided  for  the  purpose  will  be  recorded. 
The  mean  swing  thus  obtained  will  be  published  in  com- 
parison with  that  given  by  a  charge  of  Gelignite  containing 
60  per  cent,  of  nitroglycerine." 

"  Every  shot  will  be  fired  electrically,  and  in  the  case  of 
high  explosives  a  detonator  of  the  size  recommended  by  the 
manufacturer  or  the  person  submitting  the  explosive  will, 
subject  to  the  approval  of  the  Home  Office,  be  used." 

"  Each  shot  will  be  fired  in  the  case,  wrapper  or  covering 
in  which  the  explosive  is  proposed  to  be  employed  in  actual 
use." 

"  An  explosive  will  be  considered  to  have  passed  the  test 
if- 

"  (i)  The  '  maximum  charge  '  as  above  determined,  is  not 

less  than  eight  ounces. 

"  (2)  If   in  the  shots  at  the  pendulum  no  appreciable 
amount  of  the  charge  has  been  left  unexploded. 
"  (3)  If,  in  the  opinion  of  the  officer  in  charge  of  the 
testing,  the  explosive  has  exploded  in  a  satisfactory 
manner  when  fired  untamped  at  the  gallery." 
"  The  heaviest  charge  which  may  be  fired  from  the  gun 
is  2}  Ibs." 

The  following  are  extracts  from  the  chief  conditions 
governing  the  packing  and  use  of  Permitted  Explosives  (Coal 
Mines  Act,  Order  in  Council,  Sept.  ist,  1913)  :— 

"  No  drill  shall  be  used  for  boring  a  shot  hole  unless  it 
allows  at  least  a  clearance  of  J  in.  over  the  diameter  of  the 
cartridge  which  is  intended  to  be  used  in  the  shot  hole." 


126  EXPLOSIVES 

"  Every  charge  shall  .  .  .  have  sufficient  stemming,  and 
each  such  charge  shall  consist  of  a  cartridge  or  cartridges  of 
not  more  than  one  description  of  explosive." 

"  In  all  coal  mines  in  which  inflammable  gas  has  been 
found  within  the  previous  three  months  in  such  quantity  as 
to  be  indicative  of  danger,  no  explosive,  other  than  a 
Permitted  Explosive  .  .  .  shall  be  used." 

"  In  all  coal  mines  which  are  not  naturally  wet  throughout 
no  explosive,  other  than  a  Permitted  Explosive  .  .  .  shall 
be  used  ...  in  any  road  or  any  dry  and  dusty  part  of  the 
mine." 

The  following  regulations  must  be  followed  as  regards 
packing  and  marking,  and  are  in  addition  to  those  made 
under  the  Explosives  Act,  1875  : — 

Every  outer  package  must  bear  the  words  "  As  defined  in 
the  lyist  of  Permitted  Explosives." 

Each  inner  package  must  bear  the  words  "  Permitted 
Explosive,  to  be  used  only  with  not  less  than  No.  — 
detonator,"  the  number  of  the  detonator  being  that  which  is 
given  in  the  Permitted  I4st.  It  must  also  be  marked  with 
the  name  of  the  explosive,  the  name  of  the  manufacturer, 
the  place  and  date  of  manufacture,  and  the  nature  and 
proportion  of  the  ingredients  as  set  forth  in  the  Permitted 
lyist. 

Each  cartridge  must  be  stamped  with  a  P  set  in  a  crown, 
and  must  bear  the  words  "  Not  more  than  —  ounces  in  any 
one  shot  hole,"  the  number  of  ounces  being  the  maximum 
charge  as  determined  by  the  Official  Test. 

In  the  Permitted  I/ist  each  explosive  is  denned  as  con- 
sisting of  certain  ingredients,  a  maximum  and  minimum 
figure  being  given  for  each  to  allow  for  manufacturing  error. 
This  allowance,  which  is  fixed  by  the  manufacturer  with 
the  approval  of  the  Home  Office,  is  frequently  absurdly  high. 
For  example,  Super-excellite  No.  2  is  defined  as  containing 
not  more  than  6  or  less  than  4  parts  by  weight  of  nitro- 
glycerine. In  making  up  a  500-lb.  batch  with  the  mean 
value,  5  parts,  25  Ibs.  of  nitroglycerine  would  be  required,  but 
an  error  of  5  Ibs.  in  either  direction  might  be  made  without 


SAFETY  COAL  MINE  EXPLOSIVES        127 

departing  from  the  definition.  Needless  to  say  an  error  of 
5  in  25  is  absurd.  A  liberal  allowance  with  a  hygroscopic 
substance  like  ammonium  nitrate  is  more  sensible,  but  even 
here  the  allowance  is  decidedly  high.  These  high  allow- 
ances for  error  mean  that  a  manufacturer  could  make  an 
explosive  with  a  number  of  ingredients  and  submit  a  sample 
to  the  Official  Test  in  which  the  inert  matters  were  kept  at 
their  maximum  and  the  active  ingredients  at  a  minimum. 
After  having  passed  the  test  he  could  then  reverse  the  process 
and  sell  an  explosive  in  which  the  inert  material  was  at  a 
minimum,  and  the  active  ingredients  at  a  maximum,  although 
this  actual  mixture  might  not  have  passed  the  test  if  sub- 
mitted. 

The  Permitted  lyist  also  states  the  name  of  the  manu- 
facturer, and  the  situation  of  the  factory  in  which  the 
explosive  must  be  made,  the  smallest  detonator  which  may 
be  used  to  fire  the  explosive  and  the  greatest  weight  that 
may  be  used  in  any  one  shot  hole.  It  states  the  nature  of 
the  wrapper,  e.g.  parchment  paper,  tin-lead  alloy  cases,  etc., 
and  in  the  case  of  waterproofed  cartridges  states  the  nature 
of  the  waterproofing  material,  e.g.  paraffin  wax,  carnauba 
wax,  wax  and  resin,  etc.  It  does  not,  however,  set  any 
limit  to  the  relative  weight  of  the  wrapper,  although  this  is 
considerable,  especially  in  small  cartridges,  and  when  of  a 
combustible  nature  forms  a  part  of  the  explosive.  However, 
the  weight  of  the  wrapper  would  be  difficult  to  fix,  as  it 
varies  so  much  with  the  different  sizes  and,  possibly,  is  not 
of  such  importance  as  it  would  appear  to  be.  For  example, 
Ammonite  No.  i  and  Ammonite  No.  5  have  the  same  com- 
position, viz. — 

AmNO3         73-77 

T.N.N 4-6 

NaCl             19-5-21-5 

H2O              o-i 

but  No.  5  is  made  up  in  waxed  paper  cartridges,  whereas 
No.  i  is  made  up  in  cases  "  of  lead  and  tin  alloy  thoroughly 
waterproofed  with  pure  paraffin  wax."  The  former  gives 


128  EXPLOSIVES 

a  swing  of  2*41  in.  with  the  ballistic  pendulum  and  has  a 
maximum  charge  of  26  oz.,  whereas  the  latter  gives  a 
swing  of  2*42  in.,  and  has  a  maximum  charge  of  24  oz. 
These  figures  are  very  close,  but  it  must  be  borne  in 
mind  that  both  are  stated  to  be  waxed,  and  that  Ammonite 
contains  a  very  large  excess  of  oxygen  over  and  above  that 
required  for  the  complete  combustion  of  the  trinitronaphtha- 
line  present.  The  case  might  be  quite  different  with  those 
explosives  which  contain  only  just  sufficient  oxygen  for 
complete  combustion,  as  the  waxed  wrapper  would  then 
cause  the  production  of  large  quantities  of  carbon  monoxide. 
In  order  to  examine  the  influence  of  the  wrapper  two 
series  of  experiments  were  carried  out  in  the  Belgian  galleries. 
In  the  first  series  Grisounite  roche,  an  explosive  containing  a 
considerable  excess  of  oxygen  and  having  the  composition— 

AmNO3  . .         . .         . .  91*5 

D.N.T.  ..         8-5 

was  used,  and  the  combustible  gas  in  the  products  of  com- 
bustion estimated.    The  results  obtained  were  striking— 

Per  cent. 
Wrapper.  combustible  gas. 

None    . .         . .         . .          . .         .  .          . .  2*4 

Asbestos  paper          . .         . .         . .         .  .  4*0 

Paraffined  paper        . .         . .         . .  20*0 

Aluminium  or  tinfoil            . .         . .         . .  2*0 

Paraffined  paper  plus  20  grams  coal  dust . .  37*5 

Tin  foil  plus  20  grams  coal  dust     . .         . .  55*6 


The  last  figure  is  rather  extraordinary  and  seems  difficult  of 
explanation. 

In  the  second  series  of  experiments  various  Belgian  coal 
mine  explosives  were  fired  in  the  gallery  with  different 
wrappers,  and  the  charge  limite  determined.  In  all  cases  the 
use  of  paraffined  paper  in  place  of  unparaffined  paper 
lowered  the  charge  limite  to  a  very  marked  extent,  in  some 
cases  by  as  much  as  85  per  cent.,  both  when  fired  into  gas 
and  when  fired  into  coal  dust.  Metal  foil  also  reduced  the 
charge  limite  but  to  a  lesser  extent,  this  reduction  being 


SAFETY  COAL  MINE  EXPLOSIVES        129 

probably  due  partly  to  the  great  heat  of  combustion  of  the 
metal.  The  substitution  of  asbestos  paper  for  ordinary 
paper,  on  the  other  hand,  was  found  to  raise  the  charge  limite 
by  as  much  as  50  per  cent.  From  this  it  is  obvious  that  the 
effect  of  the  wrapper  is  very  great,  but  no  data  are  available 
as  to  the  influence  of  wrappers  on  different  sizes  of  cartridges, 
nor  do  any  experiments  seem  to  have  been  carried  out  in 
this  country. 

In  gallery  tests  the  diameter  and  length  of  the  bore  hole 
of  the  gun  used  affects  the  test  to  a  marked  extent,  and 
experiments  have  been  carried  out  in  Germany  on  these 
lines.  Two  guns  were  used,  one  having  a  bore  55  mm.  in 
diameter  and  57*5  cm.  long,  and  one  having  a  bore  40  mm. 
in  diameter  and  70  cm.  long.  It  was  found  that  when 
fired  from  the  55  mm.  gun  cartridges  of  35  mm.  diameter 
gave  decidedly  higher  maximum  charges  when  fired  into  gas 
than  cartridges  of  55  mm.  diameter,  whereas  with  coal  dust 
there  was  but  little  difference.  On  the  other  hand,  35  mm. 
cartridges  fired  from  a  40  mm.  gun  gave  slightly  higher  charges 
both  in  gas  and  in  coal  dust  than  did  40  mm.  cartridges. 

The  length  of  the  bore  hole  has  also  a  considerable 
influence,  the  longer  the  hole  the  bigger  the  maximum  charge 
obtained,  but  this  is  probably  due  to  the  increased  cooling 
surface  of  the  metal.  The  influence  of  the  magnitude  of  the 
sectional  area  of  the  gallery  has  also  been  studied,  and  a 
decreasing  area  is  accompanied  by  a  decreasing  charge 
limite,  but  results  are  very  irregular.  In  some  cases  the 
reduction  is  greatest  when  the  explosive  is  fired  into  gas,  and 
in  others  the  reduction  is  greater  when  coal  dust  is  used. 

No  gallery  test  can  be  said  to  represent  the  conditions 
actually  attained  in  mining  practice,  but  they  all  err  on  the 
safe  side  by  providing  for  conditions  more  dangerous  than  are 
likely  to  be  met  with.  Tamping  has  a  great  influence,  and 
the  absence  of  tamping  makes  the  gallery  tests  much  more 
severe,  whereas  in  blasting,  of  course,  shots  are  never  fired 
without  stemming. 

As  regards  the  British  test,  this  differs  from  the  Belgian 
and  American  tests  by  not  specifying  any  temperature  for 
T. 


130  EXPLOSIVES 

the  gas  in  the  explosion  chamber,  although  workings  are 
frequently  decidedly  warm.  Another  point  which  seems  to 
be  completely  overlooked  is  barometric  pressure.  Some 
workings  are  several  thousand  feet  deep,  and  as  the  baro- 
metric height  increases  by  about  -f6  in.  for  every  hundred 
feet  descended,  the  increased  pressure  in  these  workings  is 
considerable.  Surface  variations  of  barometer  in  this 
country  do  not,  as  a  rule,  exceed  i  in.,  corresponding  to 
a  depth  of  1000  ft.,  but  pending  properly  constituted  experi- 
ments it  would  be  an  advantage  if  the  barometer  reading 
and  temperature  of  the  gas  at  the  time  of  the  test  was  stated 
in  the  Permitted  Ivist.  Owing  to  the  slight  variations  of 
barometric  pressure  experienced  the  information  might  not 
be  of  great  value,  but  the  trouble  would  be  so  slight  that  it 
would  be  worth  doing.  As  will  be  seen  from  the  above 
remarks,  a  vast  amount  of  experimental  work  should  be 
carried  out  on  the  use  of  explosives  in  the  presence  of  in- 
flammable gas  mixtures  and  coal  dust.  So  far  no  work  at  all 
seems  to  have  been  done  in  this  country,  except  the  official 
testing  of  explosives  for  manufacturers.  Owing  to  the 
expense  it  is  hardly  work  that  a  private  individual,  or  even 
a  company,  would  care  to  take  up,  and  from  the  national 
importance  of  the  subject  it  is  decidedly  one  that  should  be 
taken  in  hand  by  the  Government.  The  Rotherham  station 
has  now  been  in  use  for  six  years,  but  so  far  there  seems  to 
have  been  no  attempt  made  to  carry  out  any  research.  The 
subjects  that  particularly  require  investigating  are  :  (i)  the 
influence  of  the  wrapper;  (2)  the  influence  of  barometric 
pressure ;  (3)  the  relative  efficiency  of  the  various  "  coolers  "  ; 
(4)  temperature  of  explosion;  (5)  duration  of  flame;  (6) 
velocity  of  detonation ;  and  (7)  the  diameter  of  the  cartridges. 
British  Permitted  Explosives. — The  number  of  explo- 
sives on  the  British  I^ist  of  Permitted  Explosives  is  now  (1919) 
77.  Of  these  all  the  non-hygroscopic  explosives  are  put  up 
in  cartridges  of  parchment  paper,  whereas  with  one  or  two 
exceptions  the  hygroscopic  explosives  are  put  up  in  paper 
cases  made  thoroughly  waterproof  with  a  wax  such  as 
paraffin,  carnauba  or  ceresin  wax,  or  with  a  mixture  of  wax 


SAFETY   COAL   MINE  EXPLOSIVES        131 

and  resin.  Of  the  exceptions  Stanford  Powder,  Ammonite 
No.  i  and  Ammonite  No.  4  are  put  up  in  cases  made  of  lead 
and  tin  alloy,  thoroughly  waterproofed  with  wax ;  and 
Abelite  No.  4  is  put  up  in  a  waxed  paper  case  "  with  or 
without  an  additional  covering  of  tin  foil."  A  German  ex- 
plosive, Tutol  No.  2,  which  was  on  the  list  at  the  outbreak  of 
the  war,  was  put  up  in  a  non- waterproofed  wrapper  of  parch- 
ment paper  and  an  outer  wrapper  of  waterproofed  paper, 
this  outer  wrapper  being  removed  before  charging  the  shot 
hole.  This  was  an  obvious  attempt  to  get  over  the  influence 
of  the  wrapper  as  far  as  possible,  and  although  the  explosive 
is  no  longer  on  the  Permitted  I^ist  it  is  worth  giving  its 
composition — 

N.G 24-26 

NaNO3 28-30 

NaCl        8-5-10-5 

W.M 31-34 

NaHC03  o--5 

H20         2-5-5 

It  gave  a  swing  at  the  ballistic  pendulum  of  2'ii  in.,  as 
compared  with  3-27  in.  given  by  an  equal  weight  of 
Gelignite  containing  60  per  cent,  of  nitroglycerine,  and  the 
maximum  charge  was  22  oz. 

It  is  difficult  to  classify  the  explosives  on  the  list,  but, 
roughly,  they  fall  into  three  groups,  viz.  (i)  those  containing 
no  nitroglycerine,  but  consisting  of  a  nitroaromatic  hydro- 
carbon in  conjunction  with  ammonium  nitrate  with  or 
without  sodium  or  potassium  nitrate  ;  (2)  those  containing 
nitroglycerine  and  combustible  matter  in  conjunction  with 
a  nitrate  ;  (3)  those  containing  potassium  perchlorate. 

It  is  noticeable  that  the  only  explosives  containing  barium 
nitrate  are  those  rich  in  nitroglycerine  (20-30  per  cent.)  and 
containing  no  nitroaromatic  compound,  and  that  all  the 
perchlorate  explosives  are  also  rich  in  nitroglycerine  (20-40 
per  cent.)  except  Sunderite,  which  contains  only  8-10  parts. 

Of  the  "  coolers,"  the  chlorides  of  sodium,  potassium  and 
ammonium  are  all  used,  of  which  the  potassium  salt  seems  to 
be  the  most  effective.  Ammonium  chloride  tends  to  spoil 


132 


EXPLOSIVES 


detonation,  and  in  any  case  can  only  be  used  in  conjunction 
with  sodium  or  potassium  nitrate,  as  a  fixed  base  must  be 
provided  with  which  the  chlorine  liberated  can  combine. 
Ammonium  oxalate  is  also  used  as  a  cooler,  but  its  use  up 
to  the  present  is  confined  to  explosives  containing  nitro- 
glycerine. It  is  present  in  large  quantity,  25-40  per  cent., 
in  all  the  perchlorate  mixtures  except  Samsonite  No.  2. 

The  most  powerful  explosive  on  the  list  is  Victor  Powder, 
containing  about  9  per  cent,  of  nitroglycerine  and  giving  a 
swing  of  2*96  in.,  the  next  most  powerful  being  Nationalite 
No.  i,  containing  as  explosive  ingredients  only  T.N.T.  and 
ammonium  nitrate,  and  giving  a  swing  of  2*91  in. 

No  attempt  will  be  made  to  enumerate  all  the  explosives 
on  the  list,  but  the  following  tables  give  some  of  the  chief 
ones  arranged  for  purposes  of  comparison.  In  all  cases,  the 
"  swing  "  is  that  given  at  the  ballistic  pendulum  by  4  oz., 
and  is  to  be  compared  with  the  swing  of  3*27  in.  given  by 
the  same  weight  of  Gelignite  containing  60  per  cent,  of  nitro- 
glycerine. 

The  mean  value  of  the  maximum  and  minimum  parts  by 
weight  as  set  forth  in  the  L,ist  of  Permitted  Explosives  is 
given  in  all  cases. 

EXPLOSIVES  CONTAINING  NO  NG. 


gu 

rt  "> 

Explosive. 

H 

« 

o 
£ 

0* 

n 

O 

•. 

• 

3 

t'n 
C 

u  C 
J  O 

/H 

& 

e 

fc 

rt 

d 

rt 

a 

e* 

S3 

H 

Q 

fc 

fc 

K 

W 

s 

Bellite  No.  2 

_ 

12 

61 

_ 

_ 



27 

. 

'35 

2-42 

32* 

Bellite  No.  4 

— 

13 

68-5 

— 



— 

18 

— 

7.5 

272 

12 

Abelite  No.  i 

67 

7 

68 

— 

—  - 

— 

17*5 

— 

'5 

2-85 

14 

Nationalite   No.    i 

1.5 

•  — 

66 

— 

— 

—  • 

I9'5 

— 

'5 

2-92 

12 

Bellite  No.  i  f 

15 

— 

63-5 

— 



— 

16-5 

—  • 

— 

274 

20 

Nationalite  No.   2 

15 

— 

63-5 

— 



21 

— 

—  . 

•5 

2-63 

20 

Roburite  No.  4 

16-5 

— 

60  '5 

•  — 

-  — 

— 

22*5 

— 

75 

2-86 

18 

Kentite 

15 

— 

34 

33*5 

— 

—  • 



I7 

i 

2*64 

18 

Anchorite..          .  .  '  12 

— 

34 

— 

33 



—  • 

20 

75 

273 

14 

Expedite  .  .          .  .     12 

— 

34*5 

33 

•  — 



— 

2O 

75 

2-62 

32 

Denaby  Powder  ..13 

— 

34 

33*5 

— 





*9'5 

75 

274 

18 

Super-Curtisite    .  .     10 

— 

29'5 

— 





22 

i 

271 

16 

1 

*  This  was  the  largest  charge  that  could  be  loaded  into  the  gun. 
f  Contains  also  3*5-5 '5  parts  of  starch. 


COAL  MINE  EXPLOSIVES        133 

In  the  preceding  table  the  following  comparisons  are  in- 
teresting. Bellite  No.  4  and  Abelite  No.  i  are  almost  identi- 
cal in  composition,  except  that  in  the  latter  half  the  D.N.B. 
has  been  replaced  by  an  equal  weight  of  T.N.T.  This  has 
increased  the  power  and  at  the  same  time  raised  the  maxi- 
mum charge  by  2  oz.  In  Nationalite  No.  i  the  substitution 
has  been  taken  further,  with  the  result  that  still  greater 
power  is  obtained,  although  the  maximum  charge  has  fallen 
back  to  12  oz.  Bellite  No.  i  differs  only  from  Nationalite 
No.  i  in  containing  less  salt  and  rather  less  ammonium 
nitrate  which,  surprisingly  enough,  has  caused  a  falling  off 
in  power  and  an  increase  in  the  maximum  charge.  This  may 
be  due  to  influence  of  wrapper,  or  more  likely  to  a  different 
method  of  incorporating  the  ingredients.  Anchorite  and 
Expedite  are  very  similar  in  composition,  although  the 
maximum  charges  show  a  big  difference. 

The  following  permitted  explosives  contain  no  nitro- 
glycerine, and  all  contain  a  very  large  excess  of  oxygen  over 
and  above  that  required  for  the  complete  combination  of 
the  oxidizable  ingredients  : — 
EXPLOSIVES  CONTAINING  NO  N.G.  BUT  A  LARGE  EXCESS  OF  OXYGEN. 


Explosive. 

H 

55 

55* 
Jzj 

jzs 

fc 

i 

a 

o 

i 

—  • 

^ 

. 

"S 

!| 
1° 

H 

Q 

H 

fc 

H 

& 

« 

•< 

K 

w 

^ 

Dreadnaught 

Powder 

4 

— 

— 

75 

I5-5 

— 

— 

— 

5 

'5 

2-05 

32 

Westfalite  No.  3 

5 

—  . 

— 

59'5 

14 

— 

— 

21 

'5 

2'55 

12 

Ammonite 

5*5 

— 

73 

—  . 

21 

— 



'5 

2-44 

18 

Ammonite  No.  4 

— 

4 

— 

66 

10 

— 



20 



'5 

I  '76 

30 

Ammonite  No.  5 

— 

5 

75 

— 

— 

20-5 

— 



'5 

2*41 

26 

Ammonite  No.  i 

—  — 

—  • 

5 

75 



-—* 

20-5 

" 

*~~ 

'5 

2*42 

24 

In  the  above,  Dreadnaught  Powder  is  interesting  as  having 
a  large  maximum  charge,  although  it  contains  very  little 
cooler.  Also  the  difference  in  the  maximum  charges  of 
Ammonite  and  Ammonite  No.  5  is  bigger  than  one  would 
expect  from  the  slight  difference  in  composition.  The  only 
difference  between  the  composition  of  Ammonite  No.  i  and 
Ammonite  No.  5  is  that  the  latter  is  put  up  in  waxed  paper 
and  the  former  in  metal  foil  cases. 


134 


EXPLOSIVES 

EXPLOSIVES  POOR  IN  N.G. 


Explosive. 

o* 
fc 

i 

n 

| 

i 
» 

f 

4 

1 

i 

H 

O 

5 
< 

O^ 

sT 

t 

1 

&  . 

I-  *~* 
JO  « 

Jl 

Super-Excellite 

4-2 

3 

75'2 

7-2 

_ 

_ 

_ 

_ 

10 

75 

274 

10 

Super-Excellite 
No.  2  .  . 

5 



50 

20 

__ 

^ 

__ 

5 

15 

75 

272 

14 

A  i  Monobel     .  . 

10 

— 

60 





— 

20 

i 

278 

28 

A  2  Monobel  *  .  . 

IO 

9 

59 





— 

20 

—  . 

— 

i 

2  '44 

22 

Thames    Powder 

No.  2  .  . 

10 

9 

58-5 



—  . 

21 



— 

— 

i 

2  '59 

22 

Viking   Powder* 

No.  i  .  . 

10 

9 

59 





19*5 



—  . 

— 

i 

2*44 

26 

Viking   Powder  * 

No.  2  .  . 

8'5 

8 

67 





15 



—  . 

— 

2'59 

18 

Rex  Powder 

12 

7'7 

59'5 





I9'5 



— 

— 

"2 

2'6l 

20 

Stomonal  No.    i 

10 

56 



6 

I9'5 



— 

— 

2-68 

20 

Stomonal  No.   2 

10 

6 

61 



— 

17 

—  . 

—  . 

6 

2'57 

3° 

Monobel  No.  i  .  . 

8'5 

8 

68 

— 

.  —  . 

15 

—  . 

— 

— 

2'8l 

10 

Victor  Powder  .  . 

8-5 

8 

68 



— 

15 

— 

— 

2-96 

18 

Victor       Powder 

No.  2  f 

8'5 

8 

66-5 



—  . 

— 

15 

— 

— 

I 

2-63 

16 

Du    Font's    Per- 

missible No.  i 

9*5 

7*5 

67'5 



— 

15 



— 

— 

"75 

2-82 

18 

*  Contains  in  addition '5-1*5  MgCO3.     f  Contains  in  addition  0-2  MgCO3. 

Of  the  powders  in  the  above  list  Ai  Monobel  and  Stomonal 
No.  i  both  contain  a  large  excess  of  oxygen,  this  being  reme- 
died in  the  case  of  A2  Monobel  by  the  addition  of  wood  meal. 

A2  Monobel  is  almost  identical  with  Viking  Powder  No.  i, 
except  that  in  the  latter  sodium  chloride  has  been  substituted 
for  potassium  chloride,  the  result  being  an  increased  maximum 
charge  with  the  same  power  contrary  to  what  would  be  ex- 
pected (cf.  Monobel  No.  i  and  Victor  Powder).  On  the 
other  hand,  Thames  Powder  No.  2  is  almost  identical  with 
Viking  Powder  No.  i,  but  has  a  smaller  maximum  charge, 
although  it  is  more  powerful.  As  these  explosives  are  made 
by  different  firms  the  variation  may  be  due  to  different 
mixing  or  to  a  different  amount  of  wax  on  the  wrapper. 

Victor  Powder  and  Victor  Powder  No.  2  are  very 
similar,  except  for  an  optional  0-2  per  cent,  of  magnesium 
carbonate  in  the  latter,  and  the  difference  in  power  is  quite 
remarkable.  The  official  definition  gives  in  each  case  nitro- 
glycerine 7'5-9'5,  potassium  chloride  14-16,  and  wood  meal 


SAFETY  COAL  MINE  EXPLOSIVES        135 

7-9.  For  Victor  Powder  the  ammonium  nitrate  is  given  as 
66-5-69-5,  and  for  Victor  Powder  No.  2  as  65-68  with 
magnesium  carbonate  0-2.  Consequently  without  departing 
from  the  definition  the  two  explosives  could  be  made  up  to 
have  the  same  composition,  and  this  serves  as  a  good  example 
of  the  excessive  allowance  for  manufacturing  error  permitted 
in  the  definition  (see  p.  126).  Du  Font's  Permissible  No.  i  is 
the  only  American  made  explosive  on  the  British  Permitted 
L,ist  at  present.  It  is  very  similar  to  Viking  Powder  No.  2. 
Dynobel  No.  3  and  No.  4  have  the  following  composition, 
and  represent  an  intermediate  stage  between  the  foregoing 
explosives  poor  in  nitroglycerine  and  the  explosives  rich  in 
nitroglycerine  :-  Dynobel  Dynobel 

No.  3.  No.  4. 

N.G.       . .         . .         . .         . .  14-16  14-16 

C.C '25-75  '25-75 

D.N.B.  ) 

D.N.T.  2-5-5  2-4 

T.N.T.  j 

AmNO3  51-54  44-47 

W.M 4-6  4-6 

NaCl 24-26  28-31 

MgCO3 o-i  o-i 

H2O       . .         . .         . .         . .        0-2  0-2 

Swing 2-50  2-35 

Max.  charge      . .          . .  18  oz.  30  oz. 

Dynobel  No.  2  is  similar,  but  contains  more  nitroglycerine, 

18-5-20-5  parts. 

EXPLOSIVES  RICH  IN  N.G. 


Explosive. 

0 

o 

. 

1 

cf 

~c? 

o" 

o" 

^ 

X 

O 

a 

O 

si 
'$ 

If 

S5 

o 

^ 

en 

a 

^ 

M 

X 

K 

W 

s 

Britonite  No.  2  . 

24 

_ 

35 

_ 

.  . 



30-5 

_, 

8 

3-2 

2-26 

24 

Pitite  No.  2 

24 

—  . 

34*5 

— 

— 

— 

29'5 

— 

8 

37 

2-15 

32 

Super-Kolax 

25-5 

— 

27 

7 

— 

25*5 

—  • 

7 

3 

2*10 

3° 

Super-  Kolax  No. 

28-5 

I 

28 

8-5 

5 

— 

i6'5 

— 

9'5 

3'5 

2'2I 

32* 

Cambrite  .  . 

23 

— 

33*5 

— 

3'7 

— 

27'5 

— 

8 

4*7 

1*98 

3° 

Kynarkite 

25 

— 

35 

— 

3 

— 

28 

— 

5 

3'7 

2'2I 

20 

Britonite  No.  3  . 

24'5 



~ 

_ 

28 

12 

_ 

3 

2-59 

22 

*  This  was  the  greatest  weight  that  could  be  loaded  into  the  gun. 


136  EXPLOSIVES 

It  should  be  noticed  that  Britonite  No.  2  and  Pitite  No,  2 
are  very  similar,  and  the  two  explosives  could  be  made  up  to 
have  the  same  composition  without  departing  from  their 
official  definitions,  although  the  maximum  charge  differs 
by  8  oz. 

It  will  further  be  observed  that  in  all  these  explosives  a 
large  quantity  of  wood  meal  is  used  to  absorb  the  nitro- 
glycerine, and  that,  except  in  the  case  of  Britonite  No.  3, 
deliquescent  salts  are  not  used.  This  is  on  account  of  the 
danger  of  water  being  taken  up  and  displacing  the  nitro- 
glycerine. 

A  comparison  of  Duxite  and  Arkite  No.  2  is  very  in- 
structive in  showing  the  great  difference  in  maximum  charge 
that  can  be  brought  about  by  a  slight  difference  in  composi- 
tion. Duxite  is  a  German-made  explosive  that  was  placed 
on  the  British  Permitted  I/ist  in  1914,  although  it  has  since 
been  removed.  Arkite  is  made  by  Kynoch-Arklow,  I/td., 
and  was  also  placed  on  the  list  in  1914,  and  is  still  there.  The 
official  definitions  of  these  explosives  are — 

Duxite.       Arkite  No.  2. 

N.G 31-33  31-33 

C.C 75-1*5         '5-1-5 

NaNO3    . .          . .          . .          . .  27-29 

KNO3      ..          26-28 

W.M 8-10           8-10 

AmOx.     . .         . .         . .         . .  28-31  29-31 

H2O         0-2-5          0-2 

Swing      . .         . .         . .         . .  2-45            2*41 

Max.  Charge       . .         . .         . .  12  oz.  40  oz.  * 

As  will  be  seen,  the  two  explosives  are  almost  identical, 
except  that  Duxite  contains  sodium  nitrate  in  place  of 
potassium  nitrate.  The  enormous  difference  in  the  maximum 
charges  is  probably  due  to  the  wrapper,  Arkite  No.  2  being 
put  up  in  parchment  paper  and  Duxite  in  paper  water- 
proofed with  paraffin  wax. 

The  only  Permitted  Explosive  which  is  a  true  jelly  is 
Super- Rippite.  It  is  officially  defined  as  follows  : — 

*  This  is  the  greatest  charge  which  may  be  loaded  into  the  gun. 


SAFETY  COAL  MINE  EXPLOSIVES        137 


N.G 

C.C 

KNO3 

Borax  (dried  at  100' 

KC1 

H2O  (total) 

Swing 

Max.  charge 


C. 


51-53 
2-4 


7-9 
5-8 

2'53 
18  oz. 


It  is  put  up  in  non-waterproofed  wrappers  of  parchment 
paper.  Samsonite  No.  2  and  Samsonite  No.  3  are  somewhat 
similar,  but  the  former  contains  10-12  parts  of  potassium 
perchlorate. 

The  following  explosives  containing  potassium  perchlorate 
are  on  the  Permitted  L,ist  :— 

EXPLOSIVES  CONTAINING  PERCHLORATE. 


$ 

P.H 

ff 

Explosive. 

H^ 

jd 

f? 

X 

ai 

•38 

o 

o 

*a 

« 

* 

3 

O 

a 

o 

| 

as. 

£ 

o 

H 

C/l 

& 

« 

< 

K 

W 

s 

Swale  Powder 

19 

I 

4 

_ 

9 

37*5 

28 

I 

2'50 

20 

Ajax  Powder 

22-5 

'75 

3 

— 

10-5 

37*5 

25 

'75 

2*69 

12 

Neonal     .  . 

21 

i 

'2 

— 

15 

37 

25 

i 

2-56 

16 

Dynobel  .. 

32-5 

'75 



— 

9'5 

27 

29*5 

'75 

2'6l 

22 

Herculite 

33 

i 



— 

9 

27 

29 

i 

2'72 

16 

Neonal  No.  i 

40 

2 

~ 

~ 

4*5 

H 

39*5 

'5 

2'5I 

3<> 

Among  these  it  is  noticeable  that  Dynobel  and  Herculite 
are  almost  identical  in  composition  and  could  be  made  to 
have  the  same  composition  without  departing  from  the 
official  definitions.  The  difference  of  the  maximum  charges 
is  6  oz.,  which  may  be  accounted  for  by  a  different 
method  of  mixing,  as  the  explosives  are  made  by  different 
firms,  Dynobel  being  made  by  Nobel's  Explosives  Co.,  Ltd., 
and  Herculite  by  the  British  Explosives  Syndicate. 

Bobbinite  is  a  non-detonating  explosive  of  the  gunpowder 
type  which  has  failed  to  pass  the  Rotherham  test,  but  the 
use  of  which  is  permitted  under  certain  conditions  until 
December  3ist,  1919.  There  are  two  definitions,  of  which 
the  second  is  the  most  popular — 


138  EXPLOSIVES 

ist  Definition.     2nd  Definition. 
KNO3  62-65  63-66 

c      17-19*5    18-5-20-5 

s  ..   1-5-2-5       1*5-2-5 

Ammonium  Sulphate  > 

Copper  Sulphate          5  3     7 

Paraffin  Wax           . .  . .                            7-9 

Rice  or  Maize  Starch  . .                          2-5-3-5 

Moisture       . .         . .  . .  0-2-5             °"3 

Density  (not  exceeding)  . .  1-42              1*48 

Each  pellet  must  be  coated  with  paraffin  wax  of  a  melting 
point  not  less  than  1 20 °Fahr.,  and  be  contained  in  a  wrapper 
of  brown  paper.  There  is  no  limit  to  the  charge  which  may 
be  used. 

The  conditions  for  its  use  are  as  follows : — It  may  only  be 
used  "  for  bringing  down  coal  (whether  by  shots  placed  in 
the  coal  or  by  shots  placed  in  the  stratum  immediately  above 
or  below  the  coal)  and  only  in  ...  mines  which  are  not 
liable  to  blowers  or  sudden  outbursts  of  firedamp,  and  in 
which  firedamp  does  not  exist  in  the  coal  at  a  pressure  which 
makes  the  use  of  such  explosives  dangerous,  and  in  which  the 
dust  ...  is  either  naturally  so  largely  composed  of  in- 
combustible matter  as  not  to  be  dangerous  or  has  been 
rendered  so  by  artificial  means." 

"  The  explosives  shall  only  be  used  with  an  electric  fuse 
containing  5  grains  of  gunpowder  or  with  other  means 
equally  efficient  in  igniting  the  explosive,  but  not  with  a 
detonator  or  electric  detonator." 

German  Explosives. — A  considerable  number  of 
"  Wettersichere  Sprengstoffe "  are  available  for  use  in 
German  coal  mines,  of  which  the  following  give  a  fair  idea 
of  the  types  used  : — 

Neu  Westfalit.  Wetter-Fulmenit. 

D.N.T.       ..  10-9                    T.N.T.     ..  5*5 

AmNO3      . .   70-3                    G.C.         . .  4*0 

Flour  *      ..     2-0                    AmNO3   ..  75*5 

NaCl          ..  16-8                    C  ..         ..  i'5 

Max.  charge  540  grams.          Paraffin  oil  2 '5 

NaCl  10  -o 


SAFETY  COAL  MINE  EXPLOSIVES        139 


Dahmenit. 
Naphthalene 
AmNO3 
K2Cr2O7 


T.N.T. 
AmNOg 
KNOg  . . 
Flour   .. 
Nad    .. 
Max.  Charge 

Tremonite  S.  II. 
Dinitroglycerol 

C.C 

Meal 

T.N.T 

AmNO3 
NaCl 


Dorfit  I. 

Dorfit  II. 

6 

15 

61 

65 

5 

5 

4 

4 

20 

15 

532  grams. 

300  grams. 

33 
i 

12 

2'5 
26'5 

25 


Gelatin-Carbonit. 

N.G 25*5 

C.C 7 

AmNOg  ..  v  41-5 
Glycerine  and  Gelatine  7*0 
NaCl 25*3 


Gelatin-Wetterastralit  I. 


16 
4 


Dinitrochlorhydrin 

N.G 

C.C 

M.N.T i 

D.N.T 2 

Potato  meal  8 


W.M. 
AmNOg 
NaNO3 
Am.  Ox. 
NaCl . . 
Oil 


•5 
40 

75 
2*5 
14*0 

2 


This  latter  explosive  probably  constitutes  a  record  in 
complexity  of  composition. 

Austrian  Explosives. — The  Austrian  coal  fields  are  only 
of  small  extent,  and  the  manufacture  of  explosives  is  a 
Government  monopoly.  As  a  result  only  two  explosives 
are  made  for  use  in  coal  mines.  They  are  Dynammon  and 
Wetter-Dynammon,  and  have  the  composition — 


AmNOg 

KNOg 

C 


Dynammon. 
..      87 

••      13 


Wetter-Dynammon. 

94 

2 

4 


Belgian     Explosives.  —  A    considerable    number    of 


140 


EXPLOSIVES 


explosives  are  on  the  Belgian  I,ist  of  Explosifs  S.G.P.,  of 
which  the  following  are  typical  examples  : — 

Dynamite  Antigrisouteuse  II.  Grisoutite. 


N.G. 

W.M. 

Na2SO4.ioH20 

MgS04.7H20 

Charge  limite 


N.G. 
KNO3 
Ba(N03)2  . . 
Flour 
Tan  Meal 
Na2CO3     . . 
Charge  limite 

N.G. 

T.N.T. 

KC104       . . 

AmClO4     . . 

AmNO3     . . 

NaNO3      . . 

Flour 

Glycerine  gelatine 

W.M. 

NaCl 

Charge  limite 


•  44 

.       12 

•  44 
650  grams 


44 

12 

44 
300  grams. 


Kohlen  Carbonite.      Minite. 


25 

34 

i 


25 

35 

39*5 


'5  "5 

. .  9°°  grams  750  grams. 

Permonite  S.G.P.     Yonckite  10  bis. 

..       6 

7  IO 


29*5 

4 
3 
3 

24-5 
900  grains 


25 
30 
15 


20 


A  large  number  of  ammonium  nitrate  explosives  are  also 
on  the  list  of  explosifs  S.G.P. ,  of  which  the  following  table 
gives  a  few  typical  examples  : — 


Explosive. 

n 

| 

0* 

1 

| 

o" 
9 

| 

d 

ts  9 
11 

H 

Q 

M 

fc 

o  J-— 

j 

Densite  4   .  . 
Densite  3   .  . 
Favier  2  bis. 

19 

4 

2-4 

18 
74 

45*5 

22 

~~* 

2O 

850 
700 
500 

Fractorite  B. 

—  • 

2'8 

75 

— 



2*2 

2O 

450 

SAFETY  COAL   MINE   EXPLOSIVES        141 

A  calcium  silicide  explosive,  Sabulite  Antigrisouteuse, 
is  also  on  the  list,  and  has  the  composition — 

T.N.T 6 

AmNO3             54 

KNO3 22 

Ca2Si 5 

AmCl 13 

French  Explosives. — The  French  explosifs  de  surete, 
or  explosifs  antigrisouteuses,  are  defined  by  calculation  of 
temperature  of  explosion,  and  are  divided  into  two  classes, 
viz.  "  Grisounites  roches,"  with  a  temperature  of  explosion 
of  between  1500°  C.  and  1900°  C.,  which  can  only  be  used  in 
rock,  and  Grisounites  couches  with  a  temperature  of  ex- 
plosion below  1500°  C.  which  can  be  used  in  coal.  The 
following  are  a  few  examples  : — 


Explosif. 

M.N.N. 

D.N.N. 

T.N.N. 

AmNO,. 

NaNO3. 

KN03. 

N  i  a,  bis.couche 

_ 

_ 

5 

95 

_ 

_ 

N  4  couche 

— 

-  — 

5 

90 

— 

5 

N  ib,  bis.  roche 

—  . 

8'5 

91'5 

— 

N  ic,  bis.  roche 

—  . 

I2'6 

.  —  • 

87-4 

N  2  roche  .  . 

2O 

— 

— 

80 

N  3  roche  .  . 

— 

—  • 

27 

15 

58 



LITERATURE 
COMMISSIONS 

A  summary  of  the  reports  of  the  various  commissions  first  appointed 
to  inquire  into  the  use  of  Explosives  in  coal  mines  will  be  found  in  "  Revue 
Universelle  des  Mines,"  2nd  Series,  vols.  18  and  19  (Liege,  1886).  The 
British  Report  was  published  as  an  official  document,  "  Final  Report  of 
H.M.  Commissioners  Appointed  to  Inquire  into  Accidents  in  Mines  "  (1886), 
and  the  French  Report  in  "  Annales  des  Mines,"  1888,  and  in  "  Congrds 
International  des  Mines,"  1889. 

FLAME 

C.  E.  Bichel,  "  Testing  Explosives,"  English  translation  by  A.  Larsen, 
London,  1905. 

J.C.S.I.,  1899,  p.  7. 

S.S.,  1908,  p.  408  ;    1909,  pp.  323,  343. 

P.S.,  1910,  p.  164. 

Bulletin  of  the  U.S.  Bureau  of  Mines,  No.  66. 

Reproductions  of  flame  photographs  will  also  be  found  in  A.  Marshall, 
"  Explosives,"  London,  1917. 


142  EXPLOSIVES 

GALLERIES 

The  U.S.A.  Gallery  is  described  in  detail  in  Bulletin  of  the  Bureau  of 
Mines,  No.  15.  This  publication  contains  much  interesting  information 
on  "  Permissible  Explosives,"  and  together  with  Bulletin  No.  66  should  be 
studied  by  any  one  interested  in  American  conditions.  Unfortunately  it 
does  not  give  the  composition  of  the  explosives  used. 

The  Brit]  ;h  Gallery  at  Rotherham  is  described  with  drawings  in  A.R., 
1912,  p.  83. 

An  account  of  the  Continental  galleries  will  be  found  in  A.  Marshall, 
"  Explosives,"  and  P.  F.  Chalons,  "  Les  Explosifs  Modernes." 

The  effect  of  turbulence  on  the  ignition  of  gas  mixtures  is  discussed 
in  Soc.,  1919,  p.  87. 

WRAPPERS 
"  VIII.  International  Congress  of  Applied  Chemistry,"  vol.  iv.  p.  138. 

SIZE  OF  BORE  HOLE  AND  GALLERY 
S.S.,  1910,  pp.  221,  225  ;  1911,  pp.  321,  344,  371. 

PERMITTED  EXPLOSIVES 

The  composition  of  the  explosives  on  the  British  Permitted  List  will  be 
found  in  the  following  "  Explosives  in  Coal  Mines  Orders  " : — 

September  ist,  1913.  February  3rd,  1916. 

February  loth,  1914.  April  I4th,  1916. 

April  7th,  1914.  April  26th,  1916. 

May  I3th,  1914.  September  21  st,  1916. 

June  22nd,  1914.  November  2ist,  1916. 

August  29th,  1914.  May  9th,  1917. 

January  I5th,  1915.  November  5th,  1917. 

January  28th,  1915.  May  3oth,  1918. 

April  ist,  1915.  August  2nd,  1918. 

July  3rd,  1915.  November  28th,  1918. 

August  i6th,  1915.  January  25th,  1919. 

The  composition  of  a  large  number  of  continental  explosives  is  given  in 
A.  Marshall,  "  Explosives,"  London,  1917. 


SECTION   VI.— PERCUSSION   CAPS,   DETO- 
NATORS AND  FUZES 

THE  actual  mechanism  of  detonation  is  uncertain,  but  it  is 
probably  either  a  very  rapid  wave  of  compression  raising  the 
temperature  locally  in  successive  layers,  or  it  is  a  vibration 
of  the  molecules  of  such  a  nature  that  it  causes  disruption 
into  more  stable  forms  of  matter.  In  any  case,  when  the 
majority  of  explosives  burn  the  rate  of  burning  increases 
until  it  reaches  detonation,  the  velocity  of  detonation  then 
remaining  practically  constant. 

In  order  to  be  suitable  for  use  as  an  initiator  an  explosive 
must  be  of  such  a  nature  that  the  acceleration  is  very  rapid, 
burning  passing  into  detonation  in  the  least  possible  time. 
Further,  it  must  keep  well,  and  although  for  some  purposes 
sensitiveness  to  shock  is  essential,  this  must  not  be  so  ex- 
cessive that  the  manufacture  and  handling  of  the  material 
is  accompanied  by  undue  danger. 

No  chemical  compound  fulfils  all  these  conditions,  and 
of  the  various  ones  that  have  been  proposed  from  time  to 
time  only  two  have  been  found  suitable  for  practical  purposes, 
viz.  mercury  fulminate  and  lead  azide.  Of  these  mercury 
fulminate  possesses  fair  acceleration,  and  is  not  unduly 
dangerous  to  handle  when  proper  precautions  are  taken. 
It,  however,  is  expensive,  does  not  keep  well,  and  the  mercury 
fumes  evolved  during  its  explosion  have  a  bad  effect  on  brass 
cartridge  cases.  Also,  like  all  mercury  compounds,  it  is  very 
poisonous,  and  consequently  workers  must  be  carefully  pro- 
tected from  inhaling  dust,  and  special  means  must  be  taken 
to  dispose  of  effluent  such  as  wash  water,  which  may  contain 
traces  of  mercury.  This  is  particularly  necessary  when  the 
factory  is  situated  near  rivers  containing  fish. 

I^ead  azide,  on  the  other  hand,  possesses  excellent  accelera- 
tion, and  keeps  well.  It  is  less  sensitive  than  mercury 


144  EXPLOSIVES 

fulminate  when  in  small  crystals,  but,  unlike  fulminate,  it 
readily  forms  large  crystals,  and  these  are  so  sensitive  that 
they  explode  when  touched  even  when  under  water.  It  is 
somewhat  less  expensive  and  less  poisonous  than  fulminate, 
but,  on  the  other  hand,  the  plant  required  for  its  manufacture 
is  much  more  expensive. 

Mercury  fulminate  is  still  the  most  used  initiator,  but 
lead  azide  is  coming  into  more  general  use,  and  probably 
in  the  future  will  displace  fulminate  to  a  considerable  extent. 
The  properties  required  of  an  initiator  depend  a  good  deal 
on  the  conditions  under  which  it  is  to  be  used.  Blasting 
charges  are  always  fired  by  means  of  a  fuze  or  an  electric 
current,  so  that,  provided  the  initiator  is  sensitive  to  heat, 
there  is  no  need  for  it  to  be  sensitive  to  shock.  On  the  other 
hand,  except  in  the  case  of  non-detonating  explosives  such 
as  gunpowder,  it  is  required  to  detonate  the  explosive  and  not 
merely  to  start  combustion.  Hence,  detonators  for  blasting 
purposes  require  to  be  powerful,  as  otherwise  the  charge  will 
either  be  merely  ignited,  or  detonation  will  be  incomplete. 

Propellants,  on  the  contrary,  are  not  detonated,  but 
ignited,  so  that  a  weak  initiator  is  used,  this  firing  a  priming 
composition  or  "  flaming  mixture/'  which  in  turn  fires  the 
propellant.  These  flaming  mixtures  are  of  a  very  inflammable 
nature,  and  consist  usually  either  of  fine  grain  gunpowder  or 
of  antimony  sulphide  mixed  with  an  oxidizing  agent.  In 
the  case  of  small  arms  only  slight  power  is  available,  that 
due  to  the  fall  of  the  hammer,  so  that  an  initiator  very 
sensitive  to  shock  must  be  used.  With  quick-firing  guns 
more  power  is  available.  With  heavy  ordnance  plenty  of 
power  is  available,  so  that  great  sensitiveness  is  not  required, 
and  the  initiator  in  this  case  usually  contains  no  explosive 
properly  so  called,  but  is  more  akin  to  match  composition. 
Naval  guns  and  guns  of  position  are  frequently  fired  electri- 
cally, so  that  sensitiveness  to  heat  only  is  called  for. 

Mercury  Fulminate,  Hg(ONC)2.—This  is  an  endother- 
mic  compound,  the  heat  of  formation  being  —62*9  Cal.  It 
is  always  manufactured  by  the  action  of  ethyl  alcohol  on  a 
solution  of  mercury  in  nitric  acid.  The  reaction  is  a  very 


J 


PERCUSSION  CAPS,  DETONATORS  AND  FUZE  145 

violent  one,  and  in  order  to  obtain  a  satisfactory  yield  the 
manufacture  must  be  carried  out  on  what  is  practically 
a  laboratory  scale,  only  about  3  Ibs.  of  fulminate  being  made 
at  a  time.  Several  recipes  have  been  published  differing 
only  in  minor  details,  but  the  following  description  gives  a 
good  general  idea  of  how  the  manufacture  is  usually  carried 
out. 

The  plant  consists  of  glass  bottles  or  retorts  of  about 
50  litres  capacity  each,  each  being  connected  to  a  stoneware 
or  silica  worm  condenser  and  with  a  brick  scrubbing  tower. 
Ample  draught  must  be  provided  to  draw  off  the  fumes,  as 
they  are  very  poisonous.  They  consist  largely  of  nitrous 
acid,  aldehyde,  ethyl  nitrate,  ethyl  nitrite  and  unchanged 
alcohol,  and  are  highly  inflammable.  The  process  is  carried 
out  by  dissolving  500  grams  of  mercury  in  4500  grams  of 
nitric  acid  (D  =  1400) .  The  solution  of  mercuric  nitrate  thus 
obtained  is  warmed  or  cooled  to  25°  C.,  and  5  litres  of 
94  per  cent,  spirit  added.  The  reaction  starts  after  about 
15  minutes,  and  lasts  for  about  three-quarters  of  an  hour./  If, 
however,  the  temperature  of  the  nitrate  solution  has  been 
much  below  25°  C.,  it  may  be  necessary  to  apply  gentle  heat 
in  order  to  start  the  reaction,  whereas  if  the  temperature  has 
exceeded  25  °C.,  the  reaction  maybe  uncontrollably  violent. 
XDuring  the  reaction  the  temperature  rises  to  about  85°  C., 
and  much  liquid  distils  over  and  condenses..  TMs  distillate 
is  not  of  great  value,  but  can  be  used  to  replace  part  of  the 
spirit  for  the  next  batclju"*  When  the  reaction  is  over  the 
contents  of  the  vessel  are  allowed  to  cool,  about  i  litre  of 
water  is  added,  and  the  whole  then  poured  out  into  a  porcelain 
dish,  and  the  fulminate  thoroughly  washed  with  cold  water, 
first  by  decantation  and  then  on  a  muslin  filter.  The  wash 
waters  are  collected,  made  alkaline  with  lime,  and  the 
mercury  thus  precipitated,  filtered  off,  and  recovered. 
About  10  per  cent,  of  the  total  mercury  used  is  recovered  by 
this  means,  and  after  the  precipitated  mercury  has  been 
filtered  off  the  liquors  can  usually  be  safely  run  to  waste, 
although,  as  a  matter  of  safety,  they  should  be  dealt  with 
so  that  they  do  not  find  their  way  by  infiltration  into  any 
T.  10 


146  EXPLOSIVES 

drinking  water  supply  or  into  any  stream   stocked   with 
fish. 

The  fulminate  thus  obtained  is  quite  safe  so  long  as  it 
is  preserved  wet.  It  is  only  dried  immediately  before  use, 
the  drying  being  carried  out  by  spreading  it  on  paper  trays 
in  a  stove  heated  to  35°  C.  These  stoves  usually  take  100  Ibs.  , 
and  great  care  must  be  taken  not  to  unload  them  until  the 
fulminate  is  quite  cold,  fulminate  being  much  more  sensitive 
when  warm.  Thus  obtained,  it  forms  a  grey  powder,  the 
yield  being  about  650  grams  from  500  grams  of  mercury^x 
which  corresponds  to  about  90  per  cent,  of  theory.  If  a 
little  metallic  copper  and  hydrochloric  acid  is  added  to 
the  nitrate  solution  just  before  the  spirit,  an  almost  white 
product  is  obtained,  but  this  is  less  pure  than  the  grey. 

-Culminate  has  a  specific  gravity  of  about  4-4,  and  100  c.c. 
of  water  dissolves  "07  gram  at  13°  C.,  "17  gram  at  49°  C., 
and  *8  gram  at  100°  C.  It  can  be  quantitatively  estimated 
by  titration  with  thiosulphate  — 


N  N 

Lead  Azide,  ||  ^>N  —  Pb  —  N/  ||.     In  making  lead  azide, 

W  ^ 

metallic  sodium  is  first  converted  into  sodamide,  NaNH2, 
by  heating  it  to  350°  C.  and  then  passing  a  brisk  current  of 
dry  ammonia  gas  over  the  surface.  Considerable  heat  is 
evolved,  and  by  using  a  fairly  brisk  stream  of  ammonia  the 
temperature  is  maintained  during  the  reaction  without 
external  heating.  The  reaction  is  easily  followed  by  testing 
the  gas  at  the  exit,  a  rapid  falling  off  in  the  hydrogen  content 
indicating  that  the  whole  of  the  sodium  has  been  used  up. 
The  sodamide  thus  formed  is  next  converted  into  sodium 
azide  by  heating  it  to  i5o°-25o°  C.  in  a  stream  of  nitrous 
oxide  (laughing  gas)  — 

2NaNH2  +  N2O  =  NaN3  +  NaOH  +  NH3 

The  sodium  azide  thus  formed  is  dissolved  in  water,  and 
lead  salt  thrown  down  by  double  decomposition  with  lead 


PERCUSSION  CAPS,  DETONATORS  AND  FVZE  147 

acetate.  It  forms  a  white  crystalline  powder  which  is  almost 
insoluble  in  cold  water,  and  not  much  more  so  in  hot  water. 
It  has  a  tendency  to  form  large  crystals,  and  these  may 
explode  spontaneously  even  when  under  water.  Small  or 
moderate  crystals  are  less  sensitive  to  shock  and  heat  than 
mercury  fulminate,  and  owing  to  its  high  acceleration  it  is 
more  effective  as  an  initiator.  Thus  it  has  been  found  that 
whereas  -25  gram  of  fulminate  was  required  to  detonate 
trinitrotoluol,  "05  gram  of  lead  azide  was  sufficient  under 
the  same  conditions.  It  is  chiefly  used  in  conjunction  with 
tetryl  or  T.N.T.  in  composite  detonators. 

Other  sensitive  chemical  compounds,  such  as  diazo- 
benzene  nitrate,  nitrodiazobenzene  nitrate,  lead  picrate  and 
nitrogen  sulphide  have  been  proposed  for  use  as  initiators 
from  time  to  time,  but  with  no  success,  as  in  all  cases  the 
acceleration  is  too  slow. 

Caps. — Cap  composition  for  small  arms  is  usually  a 
mixture  of  fulminate  of  mercury,  potassium  chlorate, 
antimony  sulphide  and  other  oxidizable  matter  to  which 
ground  glass  is  frequently  added  to  increase  the  sensitiveness. 
For  ordnance,  where  more  power  is  available,  the  fulminate  is 
usually  omitted.  Sometimes  gelatine  or  gum  arabic  is 
added  to  give  coherence  to  the  composition,  but  the  addition 
is  by  no  means  necessary  unless  the  mixing  is  done  wet. 

The  following  table  shows  the  composition  of  some 
British  and  Austrian  caps : — 


British 
S.M. 
(Cordite). 

British 
(Cordite). 

British 
Q.F. 
(Cordite). 

Austrian, 
for  rifles. 

Austrian, 
for  shot 
guns. 

Austrian, 
for  friction 
tubes. 

Fulminate  .  . 

8 

19 

13*7 

33'9 

KC103         ...        14 

33'3 

12 

41*5 

21-6 

66-2 

Sb2S3           ..         18 

42-9 

18 

33'4 

— 

33*1 

Meal  G.P.  .  .  !         i 

2-4 

I 

— 

S  i         i 

2-4 

I 

— 

— 

— 

Glass 

I 

10-7 

43*2 

— 

Gum 

— 

— 

— 

'7 

Gelatine      .  . 

— 

— 

—  " 

'7 

l'3 

Herz  has  suggested  the  use  of  copper  ammonium  thio- 
sulphate,  prepared  by  treating  copper  ammonium  sulphate 


148  EXPLOSIVES 

with  sodium  thiosulphate,  and  lead  thiosulphate  in  con- 
junction with  potassium  chlorate,  and  has  claimed  good 
results  with  the  following  mixtures,  although  they  do  not 
seem  to  have  come  into  use  : — 

KC103        57-3  54-5    51-5  53 

Cu(NH3)4S2O3      ..         . .  427  40-5    37-1  27-5 

PbS203      ..  7-4      5-5 

Sb2S3         . .         . .         . .  • —  11*0 

Glass         . .         . .         . .  4*0      4*0      3*0 

In  preparing  cap  composition  the  powdered  ingredients 
are  sieved  separately  and  then  mixed,  either  in  the  wet  or 
in  the  dry  state.  In  Great  Britain  and  in  France  the  mixing 
is  usually  done  dry,  but  in  Austria  and  Germany  wet  mixing 
is  frequently  preferred.  When  the  mixing  is  carried  out 
in  the  wet  way  it  is  absolutely  necessary  to  add  gum  or  other 
binding  material  to  prevent  the  ingredients  separating. 
Sufficient  water,  in  which  the  binding  material  has  been 
dissolved,  must  be  added  to  form  a  thick  mud,  but  an  exces- 
sive amount  must  be  avoided,  as  if  present  it  will  carry  away 
some  of  the  chlorate  and  also  interfere  with  the  granulating 
of  the  material.  Too  little  water,  on  the  other  hand,  renders 
the  composition  dangerous.  In  any  case,  great  care  must  be 
taken  that  none  of  the  composition  gets  on  to  the  edge  of  the 
mixing  dish  and  becomes  dry.  In  order  to  avoid  loss  of 
chlorate  by  solution  in  the  water,  alcohol  is  sometimes  added, 
as  by  this  means  the  solubility  of  the  chlorate  is  greatly 
lowered.  In  any  case,  after  mixing  the  composition  is 
granulated  by  rubbing  through  horse-hair  or  silk  sieves,  and 
then  dried  and  sifted.  It  is  not  advisable  to  load  the  caps 
with  the  wet  composition  and  then  dry  them  as  was  done  at 
one  time,  as  under  these  conditions  the  composition  is  apt  to 
form  a  hard  mass  which  is  unduly  sensitive.  For  use  in 
the  wet  process  the  fulminate  is  not,  of  course,  dried,  the 
paste  containing  about  15  per  cent,  of  water  being  used. 
When  mixing  by  the  dry  method  the  ingredients,  with  the 
exception  of  the  fulminate,  are  first  mixed,  the  fulminate 
then  added  and  the  mixing  repeated.  The  object  of  this 


PERCUSSION  CAPS,  DETONATORS  AND  FUZE  149 

procedure  is,  of  course,  to  do  as  much  of  the  mixing  as 
possible  before  adding  the  dangerous  fulminate.  Owing 
to  the  dangerous  nature  of  the  substances  dealt  with  the 
mixing  is  done  in  very  small  quantities,  from  one-half  pound 
to  two  pounds  being  the  usual  charge.  The  plant  used  is 
very  simple,  and  consists  either  of  a  papier  mache  drum 
revolved  by  hand,  or  of  a  cloth  or  light  leather  "  jelly-bag." 
When  the  drum  method  is  used  the  preliminary  mixing  of 
the  ingredients  other  than  the  fulminate  is  assisted  by  the 
addition  of  soft  rubber  balls,  thus  converting  the  papier 
mache  drum  into  a  sort  of  crude  ball  mill.  These  balls  are 
removed,  however,  before  the  fulminate  is  added. 

The  "  jelly-bag  "  is  probably  the  best  and  most  used 
mixing  machine,  and  is  shown  in  Fig.  22.  It  consists  of  a 
conical  bag  of  cloth  or  light  leather,  the  upper  and  wider  end 
being  attached  to  a  frame.  To  the  inside  of  the  apex  is 
attached  a  cord  carried  over  pulleys  to  the  operator,  who  is 
at  a  safe  distance  and  behind  a  suitable  screen.  By  pulling 
the  cord  the  bottom  of  the  bag  is  raised,  thus  turning  over 
the  contents  and  mixing  them,  a  movable  stop  being  pro- 
vided to  prevent  the  cord  being  pulled  too  far  and  thus  causing 
the  contents  of  the  bag  to  be  spilt.  On  releasing  the  cord 
the  bag  is  returned  to  its  normal  position,  either  by  the 
weight  of  the  composition  or  by  a  counterpoise.  Some- 
times rubber  discs  are  added  to  make  the  mixing  more 
thorough.  During  the  mixing  a  vessel  of  water  is  placed 
under  the  bag  to  catch  any  composition  which  may  be 
accidentally  upset,  but  when  mixing  is  complete  this  is 
replaced  by  a  paper  box.  The  operator  then  retires  behind 
the  screen,  removes  the  movable  stop,  and,  by  pulling  the 
cord,  turns  the  bag  outside  in,  the  composition  being  guided 
into  the  cardboard  box  by  the  conical  funnel  surrounding 
the  bag.  The  method  is  extremely  safe,  as  even  should  a 
charge  explode  during  mixing  the  operator  is  well  pro- 
tected. To  allow  the  operator  to  watch  the  bag  a  narrow 
slit  may  be  made  in  the  screen,  but  a  window  of  Triplex 
safety  glass  would  probably  be  more  satisfactory.  This 
has  been  tested  officially  with  most  encouraging  results, 


150 


EXPLOSIVES 


a 


n"   "D 


FIG.  22.— Jelly-bag  Mixing  Machine  for  Cap  and  Detonator  Composition. 


PERCUSSION  CAPS,  DETONATORS  AND  FUZE  151 


the  following  description  of  the  test  being   taken   from 
4  .£.,19x7:— 

"  A  block  of  Triplex  Safety  Glass  2|  in.  thick  was  securely 
fixed  by  |-in.  angle  iron  plates  to  a  screen  of  timber  3  in.  thick, 
and  4500  grains  weight  of  fulminate  of  mercury  was  fired  close 
underneath  the  glass.  The  result  was  to  shatter  the  wooden 
screen  work,  large  pieces  of  timber  flying  150-200  ft.  in  the 
air,  but  the  Triplex  glass,  although  cracked  in  all  directions, 
was  found  to  be  absolutely  whole — a  clear  demonstration 
of  the  great  protection  to  an  operator  that  would  be  afforded 
by  this  glass  during  work  with  detonators." 

The  metallic  cap  cases  are  stamped  out  of  sheet  copper, 


FIG.  23. — Percussion  Cap  Filling  Machine. 

or,  less  frequently,  brass,  and  are  varnished  internally.  The 
composition  is  filled  in  in  the  following  manner :  The  cases 
are  placed  in  depressions  in  a  bronze  plate,  called  a  "  hand," 
1000  being  the  usual  number.  Another  plate,  usually 
made  of  ebonite,  is  then  placed  on  the  "  hand,"  this  plate 
having  perforations  corresponding  to  the  depressions  in 
the  "  hand,"  but  is  placed  in  such  a  position  that  the  rows 
of  perforations  come  between  the  rows  of  depressions 
(Fig.  23).  The  thickness  of  the  upper  plate  is  so  chosen  that 
the  correct  weight  of  composition  just  fills  the  perforations. 
Rather  more  than  the  weight  of  composition  required  to  fill 
1000  caps  is  then  placed  on  the  upper  plate  and  brushed  into 


152  EXPLOSIVES 

the  perforations  so  as  to  fill  them,  any  excess  of  composition 
being  removed  with  a  soft  brush.  The  operator  then  retires 
behind  a  screen  and  slides  the  upper  plate  along  the  lower 
until  the  perforations  correspond  with  the  depressions,  and 
the  composition  falls  into  the  caps.  The  upper  plate  is 
then  removed,  and  the  "hand"  placed  in  a  hydraulic  or 
mechanical  press  provided  with  a  number  of  pistons,  each 
piston  entering  one  cap.  The  pressure  applied  is  about 
200-250  Ibs.  per  cap,  and  usually  there  are  sufficient  pistons 
in  each  press  to  press  one  or  two  rows  of  caps  at  a  time,  the 
"  hand  "  being  moved  forward  in  order  to  allow  the  next 
row  to  be  treated.  After  pressing,  any  loose  composition 
is  fanned  away  and  the  caps  then  varnished  by  placing  a 
single  drop  of  alcoholic  shellac  on  the  top  of  the  composition, 
after  which  the  alcohol  is  dried  off  at  a  low  temperature.  If 
the  caps  are  to  be  transported  a  tin  disc  must  be  inserted  into 
each  (see  page  14),  and  this  is  frequently  done  in  any  case. 
It  is  fixed  by  pressing  in  presses  similar  to  those  used  for  the 
composition,  and  is  subsequently  varnished. 

Caps  only  contain  about  *5-'6  grain  (say,  -04  gram)  of 
composition,  so  that  the  amount  of  composition  required 
for  a  "  hand  "  holding  1000  caps  does  not  exceed  50  grams. 
Consequently  it  is  not  difficult  to  provide  adequate  pro- 
tection in  the  way  of  shields  for  the  workers.  Undoubtedly 
Triplex  Safety  Glass  windows  in  these  shields  will  prove  a 
great  convenience  by  allowing  the  operations  in  progress  to 
be  watched,  while  at  the  same  time  providing  adequate 
protection. 

Officially,  caps  are  defined  as  containing  not  more  than 
half  a  grain  of  composition,  or  not  more  than  *6  grain  if 
it  contains  less  than  25  per  cent,  of  fulminate.  If  they 
contain  more  they  must  be  treated  as  detonators  (see  page 
14).  Caps  can  be  roughly  tested  by  observing  the  marks 
produced  when  they  are  flashed  against  a  sheet  of  white 
paper  at  a  given  distance,  or,  more  accurately,  by  a  modifica- 
tion of  the  crusher  gauge.  More  elaborate  methods  deter- 
mine the  length  or  duration  of  the  flame,  and  the  tempera- 
ture of  explosion  is  determined  by  an  electrical  or  optical 


PERCUSSION  CAPS,  DETONATORS  AND  FUZE  153 

pyrometer.  References  to  these  methods  will  be  found  at 
the  end  of  the  section. 

The  use  of  mercury  and  antimony  is  objectionable  with 
brass  cartridge  cases,  as  these  metals  have  a  bad  effect  on  the 
brass,  but  so  far  no  satisfactory  substitutes  seem  to  have 
been  discovered.  In  the  same  way,  the  chloride  resulting 
from  the  chlorate  causes  rusting.  An  all-organic  initiator 
would  be  a  valuable  discovery,  but  so  far  has  not  been 
attained. 

Detonators. — Detonators  being  required  to  produce 
detonation  and  not  ignition  require  to  be  much  more  power- 
ful than  caps.  Until  comparatively  recently  they  have  been 
chiefly  composed  of  a  mixture  of  80  per  cent,  of  fulminate  of 
mercury  and  20  per  cent,  of  potassium  chlorate  rammed  into 
copper  tubes,  although  a  great  many  French  detonators 
contain  only  fulminate.  In  recent  years  composite  de- 
tonators have  been  largely  used  in  which  T.N:T.  or, 
better,  tetryl  is  first  pressed  into  the  case  and  a  detonating 
composition  of  fulminate  and  chlorate  or  of  lead  azide 
pressed  on  to  the  top  of  this.  These  detonators  are  practi- 
cally a  detonator  and  primer  combined,  the  fulminate  or 
azide  detonating  the  T.N.T.,  or  tetryl,  which  in  turn 
detonates  the  cartridge.  They  have  the  advantage  of  being 
cheaper  than  non-composite  detonators,  and  of  involving 
the  use  of  much  less  of  the  dangerous  fulminate.  The  small 
amount  of  fulminate  used,  however,  has  one  disadvantage, 
and  that  is  that  the  effect  of  deterioration  is  much  more 
marked.  Fulminate  does  not  keep  well,  and  if  the  amount 
is  reduced  to  a  minimum,  as  is  the  case  in  composite 
detonators,  there  is  much  greater  chance  of  irregular  results 
being  obtained.  This  objection  does  not,  of  course,  apply 
to  composite  detonators  made  up  with  lead  azide  in  place  of 
fulminate. 

The  size  of  detonators  has  been  standardized  in  all 
countries,  and  the  following  table  shows  the  sizes,  together 
with  the  charge  of  fulminate-chlorate  mixture  (80  per  cent, 
fulminate),  and  the  charges  for  a  few  composite  detonators 
of  equal  strength  : — 


154 


EXPLOSIVES 


External  dimensions. 

Charge  (grams). 

No. 

Length. 

Diameter. 

Fulminate—  KC1O3. 

T.N.T.  or  Tetryl. 

Fulminate. 

mm. 

mm. 

"3 

I 

16 

5'5 

'4 

— 

— 

2 

22 

5'5 

'54 

— 

— 

3 

26 

5*5 

•65 

—  •              1          — 

4 

28 

6-0 

•8 

-  —  . 

5 

30-32 

6-0 

ro 

'3 

'3 

6 

35 

6-0 

1*5 

•4 

"4 

7 

40-45              6-0 

2'0 

'75 

'5 

8 

5°-55              6-7 

2-5                        '9 

'5 

Of  these  Nos.  5  and  6  are  usually  used  for  nitroglycerine 
explosives,  and  No.  7  for  ammonium  nitrate  explosives. 
No.  8  is  not  much  used,  although  probably  better  results 
would  be  obtained  by  employing  somewhat  stronger 
detonators  than  is  the  custom. 

French  composite  detonators  have  been  manufactured 
containing  picric  acid,  but  they  are  somewhat  uncertain, 
and,  in  any  case,  picric  acid  in  contact  with  copper  is  most 
objectionable.  The  copper  tubes  for  detonators  are  stamped 
out  of  sheet  copper,  and  on  account  of  the  dimensions  only 
the  very  best  soft  copper  can  be  used.  The  methods  em- 
ployed in  the  filling  operation  are  much  the  same  as  those 
used  in  rilling  caps.  The  empty  cases  are  filled  into  per- 
forations in  an  ebonite  plate,  each  perforation  being  lined 
with  brass  to  prevent  distortion,  and  being  of  such  a  size, 
that  the  detonator  is  a  snug  but  not  a  tight  fit.  Usually 
only  100  detonators  are  treated  at  a  time,  the  charge  for 
each  being  measured  out  in  the  perforations  of  a  sliding  plate 
in  exactly  the  same  way  as  when  caps  are  being  filled.  The 
pressing  is  carried  out  in  presses  with  100  pistons,  each 
piston  being  a  loose  fit  in  the  detonator  so  as  to  avoid 
friction.  The  pressure  employed  is  about  250  kg.  per  cm.2 
(60  kg.  per  detonator),  and  this  raises  the  density  of  the 
charge  to  about  2*2.  By  using  higher  pressure  higher 
density  is  attained,  but  the  effectiveness  of  the  detonator 
falls  off  considerably.  After  pressing  they  are  rumbled  with 
sawdust  to  remove  any  loose  composition,  and  then  packed. 


PERCUSSION  CAPS,  DETONATORS  AND  FUZE  155 

The  British  regulations  for  packing  specify  that  the 
detonators  shall  be  packed  in  sawdust  in  tin  boxes  lined  with 
felt  or  paper,  and  that  the  ends  shall  rest  against  a  felt  pad. 
These  tin  boxes  are  packed  in  outer  cases,  and  if  the  package 
thus  formed  contains  over  1000  detonators  the  outer  case 
must  be  double,  with  a  space  of  not  less  than  3  in.  between 
the  walls.  If  over  5000  detonators  are  in  one  case,  the  case 
must  be  provided  with  handles  for  lifting,  and  the  maximum 
number  of  detonators  that  can  be  packed  in  any  case  is 
10,000. 

Detonators  in  which  the  one  end  is  left  open  are  fired 
by  means  of  a  safety  fuze,  the  end  of  the  fuse  being  pushed 
down  until  it  touches  the  composition  and  then  held  in 
place  by  constricting  the  mouth  of  the  detonator  with  a 
pair  of  pliers.  Electrical  firing,  however,  is  rapidly  increas- 
ing, and  detonators  for  this  purpose  are  known  as  electric 
detonators,  and  are  of  two  types,  viz.  high  tension  and  low 
tension.  In  the  high-tension  detonators  firing  is  brought 
about  by  an  electric  spark  passing  between  two  points  and 
igniting  a  flaming  mixture.  They  are  not  much  used  as, 
under  working  conditions,  the  high-tension  current  needed 
is  liable  to  short  circuit,  and  the  detonators  cannot  be  tested 
before  use.  I/ow-tension  detonators  are  actuated  by  the 
electrical  heating  of  a  fine  platinum  wire,  only  a  low  voltage 
current  (2-3  volts)  being  required.  They  can  be  tested 
before  use  by  determining  their  resistance  on  a  Wheatstone 
bridge,  a  sensitive  galvanometer  and  a  very  small  current 
being  used.  The  platinum  wire  might  actually  be  embedded 
in  the  composition,  but  this  system  would  be  unreliable,  as 
it  would  probably  be  broken  during  pressing,  and,  in  any  case, 
there  would  be  danger  of  friction  being  set  up  through  move- 
ments of  the  free  ends.  The  system  always  employed  is  to 
solder  a  very  fine  platinum  wire  on  to  the  leads  which  are 
in  turn  cemented  into  the  open  mouth  of  the  detonator  by 
means  of  sulphur  or  bitumen.  Previous  to  this,  however, 
a  bead  of  a  flaming  mixture  of  sulphide  of  antimony  and 
chlorate  of  potash  is  melted  on  to  the  platinum  wire.  In 
use,  the  heating  of  the  platinum  wire  ignites  this  flaming 


156  EXPLOSIVES 

mixture,  which  in  turn  ignites  the  detonator  composition. 
As  a  source  of  current  a  small  dynamo  is  generally  used,  the 
armature  being  revolved  by  depressing  a  plunger,  this  being 
geared  on  to  the  armature  by  a  rack  and  spur-wheel.  When 
almost  at  the  bottom  of  its  stroke  this  plunger  closes  the 
circuit  with  the  detonator,  this  arrangement  being  provided 
so  that  no  current  passes  until  the  speed  of  the  armature, 
and  hence  the  voltage,  has  had  time  to  reach  a  sufficient 
magnitude  to  make  ignition  certain. 

Several  methods  have  been  proposed  for  testing  de- 
tonators, such  as  the  lead  block  test,  in  which  the  detonator 
is  fired  in  a  lead  block  much  the  same  as  the  Trauzl  block 
(see  Section  VIII.)  only  smaller ;  the  crater  test,  in  which 
the  detonators  are  fired  in  contact  with  a  plate  of  J-in.  lead 
and  the  craters  produced  compared  ;  and  the  nail  test.  This 
latter  is  the  best,  and  is  carried  out  as  follows  :  The  detonator 
is  attached  to  a  4-in.  wire  nail  by  means  of  a  copper  wire  round 
its  centre,  but  is  prevented  from  actually  touching  the  nail 
by  two  bands  of  copper  wire  placed  round  the  detonator  near 
each  end,  the  wire  being  -025  in.  diameter  (23  B.W.G.).  The 
bottom  of  the  detonator  points  towards  the  head  of  the  nail, 
but  is  if  in.  from  it.  The  whole  is  then  suspended,  nail 
upwards,  by  the  leads,  as  shown  in  Fig.  24,  and  then  fired, 
care  being  taken  that  the  nail  cannot  be  hurled  against  any 
hard  substance.  The  angle  of  deformation  of  the  nail  is 
taken  as  a  measure  of  the  strength  of  the  detonator. 

Safety  Fuze. — The  object  of  safety  fuze  is  to  ignite  the 
detonator  at  an  interval  of  time  after  the  fuze  has  been 
lighted,  thus  allowing  the  shot  firer  to  get  to  a  safe  distance. 
A  fuze  must  be  reliable,  and  not  be  apt  to  go  out ;  it  must  be 
capable  of  burning  under  water  when  subaqueous  blasting 
is  being  carried  out ;  and  must  burn  at  a  constant  rate  so 
that  the  explosion  of  the  charge  does  not  take  place  before 
the  firer  has  attained  a  place  of  safety.  All  safety  fuzes 
consist  of  a  core  of  fine  grain  gunpowder  enclosed  in  an 
outer  case  of  jute,  the  outer  case  being  more  or  less  water- 
proofed according  to  the  type  of  fuze  desired.  To  prevent 
the  case  smouldering  the  jute  is  frequently  impregnated  with 


PERCUSSION  CAPS,  DETONATORS  AND  FUZE  157 

ammonium  phosphate,  or  other  suitable  neutral  salt .  Modern 
safety  fuze  has  a  very  steady  rate  of  burning  of  about 
2  ft.  per  minute. 

The  plant  necessary  for  "  spinning "  fuze  is  shown 
diagrammatically  in  Fig.  25,  and  consists  of  a  hopper  contain- 
ing gunpowder,  the  lower  end  of  which  terminates  in  a  fine 
nozzle.  A  frame  containing  from  seven  to  ten  reels  of  jute 
yarn  revolves  round  the  hopper,  the  yarn  being  carried  down 


u 


FIG.  24. — Testing  Detonators. 


FIG.  25. — Fuze  Spinning 


close  to  the  nozzle.  As  the  powder  flows  out  of  the  nozzle  the 
revolving  reels  enclose  it  in  a  loose  spiral  of  thread  which 
then  passes  through  a  narrow  tube.  As  it  issues  from  the 
lower  end  of  this  tube  another  set  of  reels  revolving  in  the 
opposite  direction  spins  another  spiral  of  thread  round  it, 
after  which  the  fuze  is  wound  on  a  drum  and  is  ready  for 
waterproofing,  etc.  In  order  to  maintain  an  even  flow  of 
powder  from  the  hopper  a  thread  is  sometimes  made  to 
pass  through  it,  the  motion  of  this  thread  preventing  the 


158  EXPLOSIVES 

orfice  becoming  choked,  and  at  the  same  time  assuring  a 
more  equal  flow  of  powder. 

For  ordinary  use  in  damp  situations  sufficient  water- 
proofing is  attained  by  passing  the  fuze  through  tar,  after 
which  it  is  wound  with  tape,  the  turns  overlapping,  and  then 
again  tarred.  For  subaqueous  work,  however,  the  fuze  is 
usually  first  treated  with  a  priming  coat  composed  of 
Stockholm  tar  and  low  grade  gutta-percha,  and  then  coated 
with  pure  gutta-percha.  To  preserve  this  from  mechanical 
damage  it  is  usually  wound  with  tarred  yarn. 

Instantaneous  Fuze. — This  is  a  rapidly  burning  fuze 
intended  for  firing  several  shots  simultaneously.  It  consists 
of  a  wick  impregnated  with  meal  powder  and  then  loosely 
spun  over  with  yarn.  The  rate  of  burning  is  about  300  ft. 
per  second,  but  it  is  little  used  now,  having  been  replaced 
by  electric  detonators  or  detonating  fuze. 

Quick-Match. — This  is  much  the  same  as  instantaneous 
fuze,  but  is  unwound  so  that  its  rate  of  burning  is  much 
slower,  viz.  about  15  ft.  per  minute.  It  is  used  to  some 
extent  in  fireworks,  e.g.  for  firing  the  bursting  charge  in  the 
heads  of  rockets. 

Slow-Match . — This  is  a  loosely  woven  hemp  cord  slightly 
impregnated  with  potassium  nitrate,  so  that  it  smoulders 
slowly.  It  is  used  chiefly  in  conjunction  with  pyrophoric 
alloys  for  cigarette  lighters,  and  takes  the  place  of  the 
tinder  used  with  the  old-fashioned  "  flint  and  steel."  It  is 
also  used  to  some  extent  for  delayed  action  mines  in  warfare. 

Detonating  Fuze. — This  is  practically  a  very  narrow 
cartridge  of  some  detonating  explosive  in  a  metal  case, 
T.N.T.  or  tetryl  being  the  explosive  most  used.  It  is  usually 
about  4  mm.  in  diameter,  and  is  put  up  in  coils  of  50  ft.  or 
more.  A  guncotton  detonating  fuze  was  at  one  time  made 
in  France  by  filling  dry  powdered  guncotton  in  a  lead  pipe 
15*5  mm.  external  diameter  and  12  mm.  internal  diameter. 
The  ends  of  the  pipe  were  then  closed  and  the  whole  drawn 
out  by  passing  through  a  series  of  holes  in  a  draw-plate  in 
much  the  same  way  that  wire  is  drawn.  These  holes 
diminished  in  diameter  from  15*5  to  5  mm.  by  intervals  of 


PERCUSSION  CAPS,  DETONATORS  AND  FUZE  159 

•5  mm.,  and  then  from  5  mm.  to  4  mm.  by  intervals  of 
•2  mm.  This  fuze  was  said  to  give  satisfactory  results, 
but  never  came  into  general  use,  and  has  now  been  displaced 
by  fuzes  containing  T.N.T.  These  are  made  by  sucking 
molten  T.N.T.  into  a  lead  pipe  by  means  of  a  vacuum,  the 
pipe  being  kept  hot  in  a  water-bath.  After  cooling,  the  fuze 
is  drawn  out  through  draw-plates,  but  as  much  narrower 
tubes  can  be  filled  by  sucking  in  a  liquid  than  is  the  case 
when  they  are  loaded  with  a  solid,  like  guncotton,  the  same 
number  of  drawings  is  not  necessary.  The  rate  of  detona- 
tion is  very  constant,  about  5000  metres  per  second,  and  the 
fuze  is  much  used  for  determining  the  rate  of  detonation  of 
explosives  (Section  VIII.).  It  is  also  used  for  the  simul- 
taneous firing  of  several  shots,  and  in  warfare  attempts  have 
been  made  to  employ  it  for  the  destruction  of  wire  entangle- 
ments. It  is  fired  by  means  of  a  detonator.  It  should  be 
noted  that  pure  T.N.T.  must  be  used  for  the  manufacture  of 
fuze,  as  the  crude  product  is  apt  to  become  plastic  on  cooling, 
and  will  then  not  detonate  properly. 

A  somewhat  different  type  of  detonating  fuze  is  used  in 
the  Austrian  army.  This  consists  of  threads  impregnated 
with  mercury  fulminate  phlegmatized  by  the  addition  of 
20  per  cent,  of  paraffin  wax.  When  fired  with  a  suitable 
detonator  its  rate  of  detonation  is  about  6000  metres  per 
second,  but  if  ignited  it  burns  quietly,  unless  it  becomes 
hot  enough  for  the  paraifin  to  meet  and  run  away  from  the 
fulminate. 

Shell  Fuzes. — These  are  of  two  types,  viz.  time  fuzes 
and  percussion  fuzes,  the  former  being  intended  to  explode 
the  shell  in  the  air  after  it  has  travelled  a  certain  distance, 
and  the  latter  to  explode  it  on  striking.  Shells  with  time 
fuzes  are  frequently  also  fitted  with  percussion  fuzes,  so  that 
they  explode  on  striking  should  the  time  fuze  fail,  whereas 
percussion  fuzes  are  often  connected  with  a  short  time  fuze 
so  that  explosion  only  takes  place  a  short  time  after  the 
shell  has  struck,  thus  giving  it  time  to  penetrate.  This  type 
of  fuze,  delayed  action  fuze,  is  much  used  for  armour  piercing 
shell,  and  for  the  bombardment  of  deep  dugouts,  as  an 


160  EXPLOSIVES 

ordinary  percussion  fuze  would  explode  the  shell  on  the 
surface,  and  thus  do  comparatively  little  damage. 

Time  fuzes  consist  of  one  or  more  rings  of  slow-burning 
gunpowder  situated  in  the  nose  of  the  shell,  and  com- 
municating with  the  burster  charge.  The  fuze  is  fired  by  a 
simple  cap  actuated  by  the  shock  of  the  propellant.  The 
rings  are  movable,  and  by  rotating  them  the  length  of  the 
powder  train  between  the  firing  cap  and  the  burster  charge 
can  be  altered.  The  rings  are  graduated  with  a  scale 
showing  the  number  of  yards  of  travel  of  the  shell,  and  the 
fuze  is  set  for  the  given  range  before  the  shell  is  inserted  in 
the  gun. 

Percussion  fuzes  are  set  either  in  the  nose  or  in  the  base 
of  the  shell,  and  are  actuated  by  the  sudden  retardation 
when  the  shell  strikes,  driving  a  pin  on  to  a  cap.  To  prevent 
the  shock  of  the  discharge  actuating  the  pin,  special  safety 
arrangements  are  provided.  These  may  take  several  forms, 
e.g.  the  pin  may  be  held  back  by  a  powerful  spring,  the 
resistance  of  which  can  only  be  overcome  by  a  very  violent 
blow  on  the  nose  of  the  shell,  or  it  can  be  provided  with  a 
safety  catch  which  is  only  released  by  the  centrifugal  force 
set  up  by  the  rotation  of  the  shell.  As  stated  above,  the 
percussion  fuze  is  often  made  to  fire  a  short  time  fuze  in 
order  to  allow  the  projectile  to  penetrate  before  bursting. 

LITERATURE 

MERCURY  FULMINATE 

"  Das  Knallquecksilber  u.  Ahnliche  Sprengstoffe,"  R.  Knoll,  Vienna, 
1908. 

S.S.,  1911,  pp.  4,  28,  44. 

LEAD  AZIDE 

Z.ang.,  1911,  p.  2089;  1914,  p.  335.  B.  25,  p.  2084.  5.S.,  1911,  p.  417; 
1914,  p.  242. 

PERCUSSION  CAPS 

Hagen  describes  the  wet  mixing  process  in  detail  in  S.5.,  1911,  pp.  201, 
224,  243,  265,  283,  308,  and  the  filling  of  caps,  with  drawings  of  the  plant 
required,  in  S.S.,  1912,  pp.  277,  297,  322,  343,  367,  388,  411,  431,  449. 

Herz  gives  details  of  trials  with  cap  composition  containing  thiocyanates 
in  5.S.,  1912,  p.  284. 

The  following  references  are  the  methods  of  testing  caps:  /. S.C.I.,  1905, 
p.  381  ;  1906,  p.  241. 


PERCUSSION  CAPS,  DETONATORS  AND  FUZE  161 

Compositions  for  use  with  friction  tubes,  and  flaming  mixtures  as  used 
for  British  Naval  and  Military  purposes,  are  described  in  the  Official 
Publications,  viz.  "  Treatise  on  Ammunition  "  (Military),  and  "  Handbook 
on  Ammunition  "  (Naval). 

DETONATORS 

S.5.,  1907,  pp.  4,  245;   1913,  pp.  167,  190,  209. 

P.S.,  xii.  p.  134. 

The  above  refer  to  fulminate  and  fulminate  composite  detonators. 
Lead  azide  detonators  are  described  in  Z.  ang.,  1911,  2098;  S.S.,  1911, 
p.  417  ;  1913,  pp.  209,  210  ;  1914,  p.  242  ;  D.R.P.  196,824,  238,942. 

A  very  interesting  critical  examination  of  the  various  methods  of  testing 
detonators  is  given  in  Bulletin  of  the  American  Bureau  of  Mines,  No.  59. 
In  this  publication  the  methods  are  described  in  detail. 

SAFETY  FUZE 

The  manufacture  of  safety  fuze,  together  with  illustrations  of  the  plant 
used,  is  treated  in  detail  inS.iS.,  1910,  pp.  87,  107,  130,  148  ;  1913,  pp.  145, 
167. 

The  X-ray  examination  of  safety  fuze  for  discontinuity  of  the  powder 
core  is  suggested  in  /. S.C.I.,  1903,  1224. 

DETONATING  FUZE 

S.S.,  1907,  p.  173  ;    1910,  p.  169  ;    1913,  p.  312. 

See  also  Chalons,  "  Les  Explosifs  Modernes,"  Paris,  1911,  p.  424. 

SHELL  FUZES 

These  are  fully  illustrated  and  described  in  the  Official  Publications. 
"  Treatise  on  Ammunition  "  and  "  Handbook  on  Ammunition." 

Also  in  R.  Willie,  "  Mechanische  Zeitziinder,"  Berlin,  1911.  D.  T. 
Hamilton,  "  Shrapnel  Shell  Manufacture,"  New  York,  1915. 

ACCIDENTS 

Accounts  of  recent  accidents  that  have  occurred  in  Great  Britain  in 
connection  with  the  manufacture  of  fulminate,  detonators,  etc.,  will  be 
found  in  S.7?.,  186,  188,  196,  199. 


T.  II 


SECTION   VII.— MATCHES,   PYROPHORIC 
ALLOYS   AND   PYROTECHNY 

MATCHES 

UNTII,  1805  the  only  mechanical  means  of  obtaining  fire  as 
distinguished  from  the  use  of  the  burning  glass,  consisted  in 
striking  sparks  with  flint  and  steel,  and  by  this  means 
igniting  tinder.  Curiously  enough  during  recent  years  this 
method  has  again  come  to  the  front  in  a  modified  form,  the 
flint  being  replaced  by  special  pyrophoric  alloys,  and  the 
tinder  by  slow-match  or  by  a  wick  soaked  in  petrol.  In 
1805  Chancel  introduced  splints  of  wood  tipped  with  a 
mixture  of  sugar  and  potassium  chlorate  mixed  with  gum, 
these  being  ignited  on  a  pad  of  asbestos  moistened  with 
concentrated  sulphuric  acid,  and  in  spite  of  their  obvious 
inconveniences  these  matches  remained  in  use  as  late  as 
1844.  The  first  friction  match  was  made  about  1806,  and 
contained  phosphorus,  but  was  not  a  practical  success,  and 
it  was  not  until  1827  that  a  satisfactory  friction  match  was 
produced.  These  were  tipped  with  a  mixture  of  potassium 
chlorate  and  antimony  sulphide,  and  were  ignited  by  drawing 
them  sharply  through  a  piece  of  glass  paper  held  between 
the  finger  and  thumb. 

The  modern  match  industry  is  a  large  one,  17,250,000 
gross  boxes,  each  containing  on  the  average  60  matches, 
being  manufactured  in  Great  Britain  in  1910,  and  this  figure 
only  representing  about  half  the  consumption,  a  similar 
amount  being  imported.  In  the  United  States  the  con- 
sumption is  about  250,000,000,000  matches  per  annum, 
corresponding  to  about  nine  matches  per  day  per  head  of 
population,  a  figure  corresponding  closely  with  the  con- 
sumption per  capitum  in  this  country. 


MATCHES  AND  PYROTECHNY  163 

Broadly,  matches  can  be  divided  into  two  divisions,  viz. 
non-safety,  or  strike- anywhere  matches,  and  safety  matches 
which  are  supposed  to  ignite  only  when  rubbed  on  a  prepared 
surface,  but  which,  as  a  matter  of  fact,  can  usually  be  ignited 
by  drawing  them  smartly  across  any  smooth  surface  of  low 
heat  conductivity,  such  as  a  sheet  of  glass  or  paper. 

Composition  for  match  heads  is  made  up  of  five  parts,  viz.  . 
(i)  oxidizable  matter,  (2)  oxidizing  agents,  (3)  inert  gritty 
matter  (to  increase  friction),  (4)  colouring  matter,  and  (5) 
binding  material.  Striking  surface  for  safety  matches  is 
usually  composed  of  inflammable  matter  only,  with  or 
without  the  addition  of  grit  to  increase  friction. 

As  oxidizable  matter,  yellow  phosphorus  was  originally 
used,  but  owing  to  its  poisonous  properties  causing  necrosis 
("  phosy-jaw  ")  among  the  workers  its  use  is  now  prohibited 
in  almost  all  countries.  It  has  been  replaced  by  sulphide 
of  phosphorus,  sulphide  of  antimony,  zinc  sulphide  and 
scarlet  phosphorus,  or  a  mixture  of  two  or  more  of  these. 
Sulphide  of  phosphorus,  P4S3,  is  generally  used  for  strike- 
anywhere  matches,  although  a  very  small  proportion  of  this 
type  of  match  is  made  up  with  scarlet  phosphorus,  and  the 
use  of  lead,  tin  and  copper  thiocyanate  has  been  proposed. 
Sulphide  of  antimony,  Sb2S3,  is  almost  universally  used  for 
safety  matches. 

As  an  oxidizing  agent  potassium  chlorate  enters  into  the 
composition  of  almost  all  match  heads,  although  potassium 
bichromate,  manganese  dioxide  and  lead  dioxide  are  also 
used. 

The  inert  gritty  matter  generally  takes  the  form  of 
powdered  glass,  whereas  pigments,  such  as  ochre,  ultra- 
marine, etc.,  are  used  to  improve  the  appearance.  The 
binding  material  is  added  in  order  to  make  the  composition 
adhere  to  the  splint  or  taper,  and  is  usually  gum  arabic  or 
dextrine. 

As  a  striking  surface,  antimony  sulphide  and  red  phos- 
phorus are  usually  made  up  with  gum  arabic  or  dextrine,  and 
then  painted  on  to  the  sides  of  the  box. 

In  the  case  of  wax  matches  the  flame  from  the  head  is 


164  EXPLOSIVES 

sufficient  to  ignite  the  taper,  but  with  wooden  matches  the 
splint  must  be  tipped  with  some  inflammable  material  in 
order  to  convey  the  ignition  from  the  head  to  the  wood. 
This  is  usually  done  by  dipping  the  splint  into  molten 
paraffin  wax  before  putting  on  the  head.  In  France,  and 
to  a  lesser  extent  in  America,  however,  sulphur  is  frequently 
used  for  this  purpose.  Such  matches  burn  at  first  with  a 
blue  flame,  evolving  sulphur  dioxide  and  giving  practically 
no  light,  and  have  therefore  been  named  "  wait-a-minute 
matches." 

To  prevent  the  splints  glowing  after  the  flame  has  been 
extinguished  most  modern  wooden  matches  are  impregnated 
with  certain  inorganic  salts.  For  this  purpose  sodium 
tungstate  is  one  of  the  most  effective  salts,  but  it  is  some- 
what expensive,  so  that  sodium  or  ammonium  phosphate  is 
generally  used,  although  zinc  sulphate,  magnesium  sulphate, 
alum  and  phosphoric  acid  have  also  been  employed. 

Various  kinds  of  timber  are  used  for  the  splints  of  wooden 
matches,  such  as  pine,  aspen,  spruce,  etc.,  and  the  same 
applies  to  the  wooden  boxes  in  which  the  matches  are 
put  up. 

In  making  up  match  composition  the  ingredients  are 
ground  separately  in  the  dry  state,  and  then  mixed  wet.  As 
a  rule  the  oxidizable  matter  and  part  of  the  inert  matter  are 
mixed  together  with  part  of  the  gum  solution  and,  separately, 
the  oxidizing  agent  is  mixed  with  the  rest  of  the  inert  matter 
and  binding  solution.  The  two  mixtures  thus  obtained  are 
then  mixed  together  to  form  the  paste  ready  for  use.  By 
adopting  this  procedure  danger  of  fire  is  reduced  to  a 
minimum,  as  the  oxidizable  matter  and  oxidizing  agent 
are  not  brought  together  until  both  are  thoroughly 
wet. 

The  actual  tipping  of  the  matches  is  a  purely  mechanical 
operation,  and  great  ingenuity  has  been  shown  in  designing 
machines  for  carrying  out  the  operation  with  the  minimum 
amount  of  labour.  These  machines  cannot  be  described 
in  detail  in  a  book  of  this  nature,  but  the  following  description 
will  give  a  general  idea  of  the  principle  on  which  they  act. 


MATCHES  AND  PYROTECHNY  165 

When  making  square  matches  the  splints  are  usually  cut 
out  in  a  separate  machine,  but  in  the  case  of  round  or  grooved 
matches  the  splints  are  usually  cut  out  by  the  same  machine 
that  tips  them.  The  taper  for  wax  matches  is,  of  course, 
made  separately  and  fed  into  the  match-making  machine 
after  being  cut  to  the  correct  length.  Otherwise  the 
operation  of  making  wax  matches  is  similar  to  that  used  for 
wooden  matches,  except  that,  of  course,  they  are  neither  im- 
pregnated nor  tipped  with  wax.  In  the  match  machine  the 
splints  are  fed  from  a  hopper  into  grooves  in  the  iron  match 
plates,  the  splints  being  made  to  enter  the  grooves  end  on. 
These  plates  are  attached  to  an  endless  chain,  and  the  hopper 
is  so  arranged  that  just  after  the  splints  have  been  wedged 
into  the  plates  the  chain  passes  over  a  pulley,  thus  leaving 
the  matches  with  the  free  ends  pointing  downwards.  The 
plates  carrying  the  splints  next  pass  over  a  bath  of  the  im- 
pregnating solution  so  that  the  splints  are  immersed,  and 
then  over  a  bath  of  molten  paraffin  so  that  the  free  ends  dip 
into  the  wax.  This  wax  usually  has  a  melting  point  of 
39°  C.,  but  is  maintained  at  a  temperature  of  ioo°-io5°  C. 
by  means  of  a  steam  jacket.  After  receiving  their  coating 
of  wax  the  ends  of  the  splints  pass  through  a  third  bath 
containing  the  match-head  composition.  This  is  made  of  a 
suitable  consistency,  so  that  a  fairly  large  ''blob"  of  it 
adheres  to  the  end  of  the  splint,  and  this  constitutes  the  head. 
After  passing  this  bath  the  chain  is  carried  upwards  to  the 
ceiling  of  the  building,  or,  what  is  better,  through  the 
ceiling  into  an  upper  chamber.  Here  it  passes  over  a  long 
series  of  rollers  in  order  to  allow  the  head  to  dry,  the  drying 
operation  being  assisted  by  hot  air.  The  chain  then  returns 
to  a  point  near  the  hopper,  where  the  finished  matches  are 
unloaded  from  the  plates,  and  mechanically  packed  into  the 
boxes,  these  boxes  being  then  mechanically  made  up  into  the 
familiar  packets  of  one  dozen  boxes.  These  packets  are 
subsequently  made  up  by  hand  into  packets  of  one  gross* 

Modern  match  machines  are  of  considerable  size,  the 
endless  chain  being  as  much  as  700  ft.  long,  and  taking  an 
hour  to  make  one  circuit.  Such  a  machine  will  turn  out 


166  EXPLOSIVES 

about  1000  gross  boxes  of  matches  in  a  single  day,  corre- 
sponding to  nearly  9,000,000  matches,  and  only  requires 
eight  girls  to  look  after  it. 

As  regards  the  composition  of  match-head  material, 
various  recipes  are  in  use.  The  heads  of  the  old  white 
phosphorus  non-safety  matches  were  composed  of — 

White  phosphorus  . .  . .  2*5  kg.  *2  kg. 

Lead  dioxide  . .  . .  —  24  kg. 

Ferric  oxide  . .  . .       '5  kg. 

Glass  . .  . .  . .  2*0  kg.  — 

Glue  . .         . .  . .  . .  2'0  kg. 

Dextrine        . .  . .  . .  —  6  kg. 

Water  . .  . .  . .  4-5  litres  4  litres 

but  the  use  of  white  phosphorus  is  now  prohibited,  modern 
strike-anywhere  matches  being  made  with  sulphide  of  phos- 
phorus, or,  to  a  very  minor  extent,  with  scarlet  phosphorus. 
Examples  of  such  compositions  are — 

P4S3 6 

Scarlet  Phosphorus             . .  —  10 

KC103           24  45 

ZnS 6 

Ochre 6 

CaCO3            —  2 

CaSO4            —  5 

Glass  . .         . .         . .  6  22 

Glue 18  10 

H20 34  45 

Of  these  the  former  is  a  French  recipe,  i  kg.  of  the  wet 
composition  being  sufficient  for  about  100,000  matches. 
Unfortunately  all  matches  containing  sulphide  of  phosphorus 
are  apt  to  deteriorate  in  moist  air  with  the  liberation  of 
sulphuretted  hydrogen.  This  can  be  remedied  to  some 
extent  by  varnishing  the  head  with  shellac  or  collodion,  but 
several  proposals  have  been  made  for  non-safety  match- head 
composition  in  which  no  sulphide  of  phosphorus  is  used. 
The  use  of  scarlet  phosphorus,  made  by  boiling  white  phos- 
phorus with  phosphorus  tribromide,  is  mentioned  above,  but 
has  never  come  into  general  use,  although  matches  made  with 


MATCHES  AND  PYROTECHNY  167 

it  are  on  the  market.  In  Germany  thiophosphites,  made  by 
heating  a  metallic  sulphide  such  as  ZnS,  Sb2S3,  or  Cu2S  with 
red  phosphorus  in  an  atmosphere  of  carbon  dioxide  to 
450°  C.,  have  been  used,  and  good  results  are  claimed  with 
the  following  mixture  : — 

Zinc  thiophosphite  . .         . .         . .         . .  '30 

KC1O3           60 

ZnO 5 

CaS04           3 

CaCO3           5 

Glass             . .         . .         . .         . .         . .  10 

Barium  cupro  thiosulphate,  BaCuS4O6,  obtained  by 
precipitating  two  molecules  of  sodium  thiosulphate  with 
one  molecule  of  cupric  chloride  and  one  molecule  of  barium 
chloride,  has  also  been  employed,  as  by  its  use  a  strike- 
anywhere  match  containing  no  phosphorus  at  all  can  TDC 
prepared.  The  following  composition  is  recommended  : — 

BaCuS4O6  13 

KC103 58 

CaSO4        10 

S 37 

Iron  filings  . .          . .          . .          . .  4*3 

Gelatine n 

Safety  matches,  as  a  rule,  are  made  up  with  sulphide  of 
antimony,  and  are  ignited  by  rubbing  on  a  surface  of  sulphide 
of  antimony  and  red  phosphorus.  Numerous  recipes  for 
composition  are  in  use,  but  the  following  may  be  taken  as 
typical : — 

Head.  Striking  surface. 

Sb2S3       . .     24  Red  Phosphorus         i 

KC103      ..     32  Sb2S3     ..         ..     -25 

K2Cr2O7  . .     12  Carbon  . .         . .     -50 

PbO2        . .     24  Dextrine  . .     -30 

Glass        . .       2 
Gum  arable      4 

but  the  compositions  used  by  different  makers  vary  widely, 
and  sulphur,  manganese  dioxide  and  ferric  oxide  are  frequently 
added. 


i68  EXPLOSIVES 

PYROPHORIC  AU,OYS 

One  of  the  oldest  methods  of  obtaining  fire  was  by 
striking  a  spark  from  flint  and  steel  and  using  this  to  ignite 
some  inflammable  material,  such  as  tinder.  The  introduc- 
tion of  matches  led  to  the  abandonment  of  this  tiresome  and 
clumsy  process,  but  the  discovery  of  pyrophoric  alloys  of 
cerium  in  1903  led  to  its  revival,  and  the  modern  "  flint  and 
steel  "  or  "  briquet/'  to  use  the  French  term,  of  which  there 
seems  to  be  no  translation,  became  such  a  serious  rival  to 
matches  that  heavy  taxes  were  imposed  on  them  by  those 
countries  in  which  the  match  industry  was  a  State  monopoly, 
or  in  which  matches  were  taxed  for  revenue  purposes.  The 
outbreak  of  war  gave  a  further  impetus  to  the  pyrophoric 
alloy  industry,  as  the  "  briquet "  was  preferred  to  matches  by 
the  troops  owing  to  its  lessened  sensibility  to  damp  and  to  the 
fact  that  the  small  quantity  of  petrol  required  could  always 
be  obtained  from  the  mechanical  transport.  The  "  briquet  " 
also  became  increasingly  popular  with  the  civilian  population 
owing  to  the  scarcity  of  matches. 

Opinions  differ  as  to  the  reason  for  the  pyrophoric 
nature  of  cerium  alloys.  The  pure  metals  of  the  cerium 
group  are  only  slightly  pyrophoric,  although  their  tempera- 
ture of  ignition  is  low,  and  it  has  been  suggested  that  the 
pyrophoric  nature  of  the  alloys  is  due  to  the  increased 
hardness  allowing  finely  divided  dust  to  be  projected  into 
the  atmosphere  and  ignited  partly  by  the  heat  generated  by 
the  friction  and  partly  by  spontaneous  combustion  due  to 
the  large  surface  exposed  to  the  oxygen  of  the  air.  It  seems 
more  probable,  however,  that  the  pyrophoric  effect  is  due 
to  the  formation  of  highly  inflammable  suboxides. 

For  the  preparation  of  pyrophoric  alloys  it  is  not 
necessary  to  use  pure  cerium,  it  being  customary  to  make  use 
of  the  crude  mixture  of  rare  earths  left  over  as  a  waste 
product  when  the  thorium  is  extracted  from  monazite  sand 
for  making  incandescent  gas  mantles.  In  order  to  reduce 
this  to  the  metallic  state  various  methods  have  been  proposed, 
such  as  reduction  with  metallic  calcium,  but  industrially 


MATCHES  AND  PYROTECHNY  169 

the  process  is  always  carried  out  electrically.  This  can  be 
done  by  the  electrolysis  of  the  oxide  in  fuzed  cerium  fluoride, 
and  on  the  laboratory  scale  this  procedure  gives  excellent 
results.  Unfortunately  the  melting-point  of  the  fluoride  is 
very  high,  about  1000°  C.,  so  that  it  has  not  been  found 
possible  to  use  this  process  on  an  industrial  scale,  and  for 
manufacturing  purposes  it  is  usual  to  electrolyze  a  mixture 
of  cerium  chloride  and  chlorides  of  the  alkali  earth  metals. 
In  order  to  obtain  satisfactory  results  the  cerium  chloride 
must  be  dry  and  free  from  oxide  and  oxychloride.  As  the 
chloride  is  soluble  in  alcohol,  whereas  the  oxide  and 
oxychloride  are  insoluble,  separation  can  be  effected  by  use 
of  this  solvent,  but  it  is  found  better  to  obtain  the  pure,  dry 
chloride  by  heating  the  crude  chloride  with  sal-ammoniac. 

The  electrolysis  is  carried  out  in  a  graphite  crucible  with 
an  iron  cathode,  and  considerable  difficulty  is  met  with 
owing  to  the  tendency  of  the  metal  to  remain  distributed 
in  the  electrolyte  in  very  finely  divided  particles,  or  in  the 
colloidal  form. 

Various  proposals  have  been  made  for  suitable  electro- 
lytes, some  investigators  recommending  a  mixture  of  two 
molecules  of  cerium  chloride  and  one  molecule  of  calcium 
chloride,  while  others  claim  good  results  with  mixtures  of 
calcium  chloride  and  fluoride  and  barium  fluoride.  For 
example,  it  is  stated  that  excellent  results  are  obtained  by 
fuzing  three  parts  of  barium  chloride  and  three  parts  of 
calcium  fluoride  with  eight  parts  of  calcium  chloride  in  an 
electric  furnace,  and  then  adding  ten  parts  of  cerium  fluoride. 

The  metal  obtained  by  electrolysis  is  usually  cast  into 
blocks  weighing  from  two  to  twenty  pounds,  and  contains 
about  80  per  cent,  of  cerium,  the  balance  being  chiefly  other 
rare  earth  metals,  and  in  this  state  it  is  quite  unsuited 
for  pyrophoric  purposes.  A  satisfactory  pyrophoric  alloy 
must  be  sufficiently  hard  to  allow  sparks  to  be  struck  with 
ease  without  being  too  hard,  and  at  the  same  time  it  must 
be  sufficiently  tough  not  to  crumble  away.  In  order  to 
obtain  these  properties  it  is  usual  to  alloy  the  crude  cerium 
metals  with  about  30  per  cent,  of  iron,  a  little  zinc  being 


170  EXPLOSIVES 

sometimes  added  to  convey  hardness,  and  sometimes  a  little 
copper  to  make  the  alloy  tougher.  The  alloying  is  carried 
out  by  heating  iron  powder  in  a  graphite  crucible  under  a 
layer  of  an  easily  fuzible  salt.  The  cerium  is  then  added 
little  by  little  when  it  melts  and  slowly  dissolves  the  iron. 
The  fuzible  salt  is  used,  of  course,  to  protect  the  alloy  from 
the  action  of  the  air,  but  in  spite  of  this  considerable  loss 
takes  place  through  oxidation,  so  that  a  pound  of  cerium 
does  not  give  much  more  than  a  pound  of  alloy.  When  the 
whole  of  the  iron  has  been  dissolved  the  melt  is  cast  either 
into  a  single  block,  which  is  afterwards  cut  up  for  sale,  or 
into  thin  rods.  Auer  metal  No.  2  is  made  somewhat 
differently,  as  the  alloy  is  cast  into  a  block  and  then 
ground  to  a  powder,  and  this  then  moulded  and  heated 
until  it  sinters  together.  The  object  of  this  process  is  to 
obtain  a  finished  stick  that  is  impregnated  with  the  lower 
oxides,  and  improved  pyrophoric  properties  are  claimed  to 
be  obtained  by  this  process. 

PYROTBCHNY 

The  art  of  making  fireworks  is  very  ancient,  the  first 
use  of  explosives  being  for  pyrotechnic  purposes.  The 
term  "  fireworks  "  includes  two  classes  of  goods,  viz.  (i) 
appliances  for  producing  illumination,  either  for  display 
purposes,  e.g.  Bengal  fire,  display  rockets,  Roman  candles, 
etc.,  or  for  military  or  life-saving  purposes,  e.g.  "  star  " 
shell,  Holme's  buoys,  etc.,  or  for  purposes  of  signalling, 
e.g.  Verey  stars,  marine  rockets  ;  and  (2)  appliances  for  pro- 
ducing sound  either  for  display,  e.g.  crackers,  or  for  signal- 
ling, e.g.  fog  signals,  maroons,  etc.  The  explosive  or  com- 
bustible materials  used  in  firework  construction  can  be 
divided  into  three  broad  groups,  viz.  slow  burning  mixtures 
for  producing  illuminating  effects,  such  as  golden  rain, 
coloured  fire,  stars,  etc.,  more  rapidly  burning  mixtures 
used  as  propellants,  e.g.  for  rockets,  Catherine  wheels,  etc., 
and  rapidly  burning  mixtures  used  for  bursting  charges  for 
rockets  and  for  the  production  of  sound.  In  some  cases 


MATCHES  AND  PYROTECHNY  171 

guncotton  us  used  as  a  sound  producer,  but  otherwise  all 
the  combustible  material,  both  fast  and  slow,  used  in  pyro- 
techny  is  of  the  gunpowder  type,  additions  of  metal  filings 
being  made  in  order  to  produce  sparks  and  barium,  copper, 
strontium,  etc.,  salts  being  added  in  order  to  produce 
colour  effects.  For  display  purposes  chlorates  are  largely 
used,  as  they  give  more  brilliant  effects  than  nitrates, 
probably  largely  owing  to  the  greater  volatility  of  the  chloride 
produced  during  combustion,  but  the  use  of  chlorates  in 
the  presence  of  sulphur  is  prohibited  in  Great  Britain.  The 
danger  of  chlorate-sulphur  mixtures  is  largely  due  to  the 
fact  that  some  of  the  sulphur  becomes  oxidized  to  sulphuric 
acid,  and  this  increases  the  rate  of  decomposition  of  the 
mixture,  the  reaction  thus  becoming  autocatalytic. 

The  basis  of  almost  all  pyrotechnic  mixtures  other  than 
coloured  lights  is  "  meal  powder,"  a  fine  grain  gunpowder 
to  which  sulphur,  nitre  or  charcoal,  or  two  or  all  of  these 
are  frequently  added  to  reduce  its  rate  of  burning. 

Fireworks  are  almost  invariably  put  up  in  paper  cases, 
these  being  made  by  hand  by  pasting  several  layers  of 
paper  together.  Rockets,  squibs,  crackers,  etc.,  are  all 
made  by  this  means,  and  even  the  "  shells  "  which  are  fired 
from  mortars  and  contain  coloured  stars  are  made  of  paper, 
although  they  are  sometimes  as  much  as  2  ft.  in  diameter. 
These  shells  are  made  by  tearing  strips  of  paper  and  pasting 
them  together  inside  a  hemispherical  mould,  layer  upon 
layer,  until  the  desired  thickness,  |  in.-i  in.,  is  attained.  The 
hemisphere  thus  formed  is  then  removed  and  dried,  after 
which  the  edge  is  trimmed  in  a  lathe  and  a  complete  shell 
formed  by  gluing  two  hemispheres  together.  The  quality 
of  the  paper  used  is  of  great  importance,  and  various  qualities 
are  used  for  different  purposes.  As  a  general  rule,  it  should 
be  free  from  all  loading  with  mineral  matter,  and  should  have 
as  great  a  mechanical  strength  as  possible. 

Coloured  fire  (Bengal  fire)  is  the  simplest  form  of 
firework,  and  simply  consists  of  a  moderately  fiercely 
burning  mixture  containing  suitable  salts  to  impart  colour 
to  the  flame,  strontium  and  calcium  being  used  to  produce 


172  EXPLOSIVES 

red,  barium  or  copper  for  green,  etc.  Many  different 
mixtures  can  be  used,  of  which  the  following  may  be  con- 
sidered typical : — 

Red.  Yellow.  Green.  Blue. 

KC103    78      NaN03    70      Ba(NO3)2    66      KC1O3  45 

SrC03     15      S             20       Sugar          33      C  5 

Shellac     7      Sb2S3        7      Shellac          i       CuCO3  10 

Carbon      3                                    HgCl  35 

Shellac  5 

Stars  are  very  similar  in  nature,  but  are  contained  in  a 
rocket  or  shell,  and  only  liberated  and  ignited  when  the 
rocket  or  shell  has  reached  its  maximum  height.  They 
are  of  two  types,  viz.  "  naked  "  or  "  pumped  "  and  "  pill- 
box." The  former  are  composed  of  a  mixture  of  carbon, 
sulphur,  meal  powder  and  a  nitrate  to  impart  the  desired 
colour,  the  ingredients  being  mixed  together  with  shellac, 
and  then  either  moulded  into  pellets  or  spread  out  and  cut 
up  into  cubes,  after  which  the  solvent  is  dried  off  and  the 
"  stars  "  loaded  direct  into  the  rocket  or  shell.  "  Naked  " 
stars  should  only  be  employed  in  fireworks  of  the  smallest 
sizes,  as  they  are  very  apt  to  crumble.  In  any  case,  to  avoid 
crumbling  it  is  very  important  to  use  shellac  or  other  binding 
material  which  is  completely  soluble  in  the  solvent  used, 
usually  methylated  spirit.  As  a  rule  no  special  device  is 
used  for  igniting  naked  stars,  ignition  being  brought  about 
by  the  burster  charge,  and  for  this  reason  they  are  almost 
invariably  composed  of  nitrate,  as  such  mixtures  are  more 
readily  ignited  than  chlorate  mixtures,  and  in  any  case  a 
naked  chlorate  star  in  contact  with  meal  powder  cannot  be 
used,  as  it  would  mean  having  a  chlorate  in  contact  with 
sulphur.  Sometimes,  however,  the  moulded  pellets  are  made 
with  a  perforation  into  which  a  piece  of  quick  match  is 
inserted  to  assist  their  ignition. 

"  Pill-box  "  stars  are  much  safer  than  "  naked  "  stars, 
and  are  put  up  in  paper  cases,  ignition  being  brought  about 
by  means  of  quick  match.  They  are  usually  chlorate 
mixtures,  e.g. — 


MATCHES  AND  PYROTECHNY  173 

Red.  Blue. 

KC103       47        56               KC103  40  37 

Sugar        21         23                Sugar  25  25 

SrCO3        22         10                Cu2S  15 

HgCl                     ii                Cu  6 

HgCl  20  32 

Green.  Yellow. 

KC103       26  KC103  59 

Sugar        22  Na  Oxalate  17 

Ba(NO3)2  30  Shellac  24 
HgCl       "  22 

Magnesium  or  aluminium  powder  is  also  sometimes 
added  in  order  to  increase  the  brilliancy. 

Floating  Stars  are  very  similar,  but  are  attached  to 
a-  parachute  of  silk  or  soft  paper.  They  are  made  to  burn 
slowly,  and  frequently  the  pellets  are  made  up  of  several 
layers,  each  layer  of  a  different  composition,  so  that  they 
change  colour  as  they  burn. 

Star  Shell  for  military  purposes  is  composed  of  barium 
and  potassium  nitrate,  magnesium  powder,  paraffin  and 
boiled  linseed  oil.  The  composition  used  by  the  British 
Army  is  made  up  of — 

Ba(NO3)2 i  Ib.  ii  oz. 

KNO3        i  Ib.  2  oz. 

Mg  . .          . .          . .          . .  i  Ib.  3  oz. 

Paraffin     .  .          . .          . .          .  .  5  oz. 

Boiled  oil  . .          . .          . .  3  per  cent. 

Whereas  the  magnesium  light  rocket  is  made  up  of — 

Ba(NO3)2 i  Ib.  8oz. 

KC1O3        . .          i  Ib.  2  oz. 

Mg  . .          . .          . .          . .  i  Ib.  8  oz. 

Boiled  oil  . .          . .          . .         . .  3  per  cent. 

the  propellant  charge  being  meal  powder. 

Squibs  are  paper  cases  with  a  small  exploding  charge  at 
one  end,  and  above  it  a  long  layer  of  slow  burning  composition 
composed  of  meal  powder  mixed  with  sulphur,  or  sulphur 


174  EXPLOSIVES 

and  charcoal.  They  are  primed  with  a  little  gunpowder, 
and  when  ignited  burn  fiercely  and  then  explode  when 
the  ignition  spreads  to  the  charge  of  gunpowder  at  the 
end. 

Catherine  Wheels  are  long,  narrow  paper  tubes  filled 
with  a  mixture  of  meal  powder  (2  parts)  and  potassium 
nitrate  (i  part)  and  sulphur  (i  part),  and  then  wrapped 
round  a  circular  wooden  disc.  When  a  pin  is  placed  through 
the  centre  of  the  disc  to  act  as  a  spindle  and  one  end  of  the 
paper  tube  ignited,  the  escaping  gas  causes  the  wheel  to 
revolve. 

Roman  Candles  are  paper  cases  containing  coloured 
stars  separated  by  layers  of  a  rather  fiercely  burning  com- 
position of  meal  powder,  nitre  sulphur  and  charcoal,  such 
as — 

Meal  powder        . .         . .  3        4        8 

KN03        4        5        2 

S i        4        2 

C 213 

This  composition  burns  fiercely  with  a  good  display  of 
sparks,  the  stars  being  ejected  by  the  gases.  Naked  stars 
are  generally  used,  and  the  composition  must  not  be  tightly 
packed,  as  otherwise  they  may  break  or  crumble. 

Whistling  Fireworks  are  paper  tubes  packed  with  a 
mixture  of  three  parts  of  potassium  pier  ate  and  two  parts  of 
potassium  nitrate.  One  end  of  the  tube  is  left  open  and  the 
other  is  closed,  the  gas  escaping  from  the  open  end  causing 
a  loud  whistling  noise.  They  are  usually  used  as  a  garniture 
for  rockets  or  shells. 

Rockets  consist  of  two  parts,  viz.  the  body  containing 
the  propellant,  and  the  head  containing  the  garniture. 
The  body  is  a  paper  tube  constricted  at  the  lower  end 
either  by  squeezing  and  then  tying  with  a  ligature,  or  by 
means  of  a  clay  plug.  In  order  to  fill  the  body  a  conical 
mould  is  inserted  through  the  constricted  end,  point  upwards, 
and  the  propellant  charge  then  added  little  by  little  and  well 
malleted  home.  There  is  considerable  skill  required  in 


MATCHES  AND  PYROTECHNY  175 

doing  this,  as  the  packing  must  be  quite  even  if  good  results 
are  to  be  obtained.  When  the  propellant  has  been  added 
the  top  is  closed  with  a  perforated  clay  plug  through  which 
a  piece  of  quick  match  passes  in  order  to  fire  the  head,  and 
the  conical  mould  then  withdrawn.  The  head  is  another 
paper  case  containing  a  burster  charge  of  gunpowder  and 
garniture  in  the  form  of  stars,  floating  stars  or  whistling 
fireworks,  and  is  glued  on  to  the  body.  The  stick  is  then 
attached  so  that  the  rocket  balances  when  supported  about 
one  inch  from  the  base.  It  is  fired  by  applying  fire  to  the 
conical  hole  left  in  the  base  by  the  mould.  The  outrush  of 
gases  causes  the  rocket  to  ascend,  and  when  at  its  maximum 
height  the  quick  match  causes  the  burster  charge  to  explode, 
thus  liberating  the  garniture.  Various  compositions  are 
used  for  the  propellant,  such  as  the  following  : — 

Meal  powder         . .         . .          . .  2  i  3 

KNO3        4  20  16 

C 2  12  8 

S i  2  4 

although  iron  filings  are  frequently  added  in  order  to  pro- 
duce a  good  train  of  sparks. 

Life-saving  Rockets  are  similar,  except  that  they  have, 
of  course,  no  garniture,  and  are  used  for  carrying  a  rope  from 
shore  to  ships  in  distress.  The  propellant  composition  is 
usually  made  up  as  follows  : — 

KNO3        7lbs. 

C atlbs. 

S 2lbs. 

Sometimes  a  head  is  provided  closely  resembling  the  body, 
so  that  when  the  original  body  is  exhausted  the  rocket 
obtains  a  fresh  impulse  due  to  the  firing  of  the  head. 

Touch  Paper  is  much  used  for  igniting  fireworks,  and 
is  made  by  brushing  paper,  usually  blue  in  colour,  on  one 
side  with  a  solution  of  potassium  nitrate  (half  a  pound  to 
the  gallon)  and  then  drying.  Slow  match  for  pyrotechnic 
purposes  is  made  by  soaking  blotting  paper  in  lead  nitrate 
solution  (2j  Ibs.  per  gallon)  and,  after  drying,  pasting  the 


176  EXPLOSIVES 

sheets  together,  usually  so  as  to  give  six  thicknesses.  Pyro- 
technic quick  match,  on  the  other  hand,  is  made  by  impreg- 
nating lamp  wick  cotton  with  a  smooth  cream  of  hot  starch 
solution  and  meal  powder,  and  then  dusting  it  over  with 
dry  powder.  Where  ordinary  quick  match  is  not  sufficiently 
rapid  it  is  threaded  through  paper  tubes,  as  the  confinement 
greatly  increases  its  rate  of  combustion.  Such  tubes  are 
known  as  leaders,  and  are  used  when  various  parts  of  a 
firework  have  to  be  ignited  almost  simultaneously. 

Fog  Signals  for  the  use  of  lighthouses  during  fog  are 
usually  composed  of  Tonite,  i.e.  guncotton  pulp  that  has 
been  impregnated  with  potassium  or  barium  nitrate,  and  then 
compressed  into  pellets  and  dried.  They  are  fired  by  means 
of  a  detonator. 

Photographic  Flash  Lights  are  required  to  give  out 
light  rich  in  actinic  rays,  and  for  this  reason  magnesium 
powder  enters  into  the  composition  of  most  of  them.  The 
original  flash  lights  were  very  simple  in  construction,  and 
consisted  of  a  little  magnesium  powder  placed  in  the  bowl 
of  a  clay  pipe,  a  piece  of  cotton  wool  soaked  in  spirit  resting 
lightly  on  the  top  of  the  bowl.  The  spirit  was  lighted  and 
the  magnesium  powder  then  blown  into  the  flame  by 
blowing  air  through  the  stem  of  the  pipe.  At  present  it  is 
usual  to  use  magnesium  powder  mixed  with  an  oxidizing 
agent  such  as  potassium  chlorate  or  per  chlorate  or  barium 
chlorate,  this  latter  salt  giving  a  safer  mixture  than  potassium 
chlorate.  Attempts  have  also  been  made  to  utilize  the  fact 
that  the  oxides  of  the  rare  earth  metals  give  off  a  great  deal 
of  light  when  incandescent  (cf.  incandescent  gas  mantles) 
and  flash  powders  composed  of  magnesium  powder  mixed 
with  thorium  or  zirconium  nitrate  have  been  placed  on  the 
market.  Barium  peroxide  has  also  been  used  as  an  oxidizing 
agent,  and  collodion  cotton  is  also  employed  to  some  extent 
as  an  ingredient. 

In  modern  flash  lights  it  is  customary  to  replace  part  of 
the  magnesium  by  the  less  expensive  aluminium  powder, 
and  good  results  have  been  claimed  with  the  following 
mixture  : — 


MATCHES  AND  PYROTECHNY  177 

Al 50 

Mg . .  . .          . .          . .   100 

Fe2O3         30 

CuC03       30 

MgS04       ..  ;.         ..5 

As  will  be  seen,  the  oxygen  is  supplied  by  the  ferric  oxide, 
so  that  this  powder  is  closely  akin  to  Thermit  in  nature. 
The  anhydrous  magnesium  sulphate  is  added  as  a  deterrent 
to  prevent  combustion  becoming  too  rapid. 

The  Holme's  Life-buoy  is  an  ordinary  life-buoy  to  which 
is  attached  a  can  containing  calcium  phosphide,  this  can 
being  closed  by  a  lightly  soldered  plug.  When  used  this  plug 
is  wrenched  out  and  the  buoy  then  thrown  into  the  sea.  The 
water  on  coming  into  contact  with  the  calcium  phosphide 
causes  an  evolution  of  the  spontaneous  inflammable  phos- 
phides of  hydrogen,  the  flame  of  which  is  visible  at  night. 
The  charge  is  usually  sufficient  to  burn  about  half  an  hour. 

LITERATURE 

MATCHES 

Freitag,  "  Zundwarenfabrikation,"  Vienna,  1907. 

Jettel,  "  Zunchvarenfabrikation,"  Berlin,  1897.  See  also  articles  in 
Thorpe's  "  Dictionary  of  Applied  Chemistry,"  vol.  iii.  and  Dammer, 
"  Chemische  Technologic  der  Neuzeit,"  vol.  i. 

The  following  patents  will  be  found  of  interest : — 

D.R.P.  101,737  ;  105,061  ;  153,188  ;  157,424  ;  165,090  ;  197,865.  Also 
Z.  ang.,  1900,  976  ;  1906,  2080  ;  B.>  35,  351  ;  36,  979,  4202.  The  last  two 
of  these  deal  with  scarlet  phosphorus. 

PYROPHORIC  ALLOYS 

H.  Kellermann,  "  Die  Cerimetalle  u.  ihre  pyrophoren  Legierungen," 
Halle,  1912. 

C.  R.  Bohm,  "  Die  Verwendung  der  Seltenen  Erden,"  Leipzig,  1913. 

O.  Dammer,  "  Chemische  Technologic  der  Neuzeit,"  vol.  i. 

R.  Ullmann,  "  Enzyklopadie  der  technischen  Chemie,"  vol.  ii. 

The  following  patents  and  references  will  also  be  found  of  interest : — 

D.R.P.  154,807  ;    172,529  ;   263,301  ;   268,827. 

Ghent.  Ind.,  1913,  pp.  195,  235. 

Annalen  der  Chemie,  320,  231  ;   331,  i,  45  ;   355,  116. 

PYROTECHNY 

There  seems  to  be  no  modern  works  dealing  with  Pyrotechny,  but 
A.  Bujard,  "  Leitfaden  der  Pyrotechnik,"  Stuttgart,  1889,  gives  a  fair  idea 
of  the  subject.  An  interesting  article  will  also  be  found  in  Thorpe's 
"  Dictionary  of  Applied  Chemistry,"  but  it  requires  to  be  read  with  care, 
as  a  large  number  of  the  compositions  described  are  out  of  date  and  illegal. 

See  also  the  article  on  "  Feuerwerkerei  "  in  Ullmann's  "  Enzyklopadie 
der  technischen  Chemie,"  vol.  v. 

T.  12 


SECTION  VIII.— EXPLOSIVE  PROPERTIES 

APART  from  analytical  operations  certain  tests  are  applied 
to  explosives  in  order  to  determine  their  properties.  These 
tests  may  be  roughly  divided  into  two  classes,  viz.  tests 
to  determine  the  nature  of  the  explosive  and  tests  to  deter- 
mine its  stability.  The  former  includes  tests  for  power, 
violence  and  velocity  of  detonation,  pressure,  heat  and 
temperature  of  explosion,  and  production  of  flame,  whereas 
the  latter  includes  tests  for  chemical  stability,  of  which  the 
Abel  heat  test  is  the  most  important,  and  tests  for  sensitive- 
ness to  heat  and  mechanical  shock.  In  addition,  propellants 
are  tested  to  determine  the  velocity  of  the  projectile  and  the 
pressure  attained  in  the  gun,  and,  of  course,  these  tests  must 
be  carried  out  with  the  type  of  arm  for  which  the  explosive 
is  intended.  Explosives  for  use  in  coal  mines  are  further 
tested  to  determine  their  safety  when  fired  in  the  presence 
of  fire  damp  and  coal  dust,  and  these  tests,  together  with  the 
methods  used  for  studying  flame  production,  have  already 
been  described  in  Section  V. 

TESTS  FOR  POWER 

The  power  of  an  explosive  is  its  capacity  for  doing  useful 
work,  and  must  not  be  confused  with  violence  or  brisance, 
this  latter  being  rather  the  rate  at  which  work  is  done,  or 
the  shattering  effect  produced.  It  is  impossible  to  measure 
the  power  of  an  explosive  in  definite  units  such  as  foot- 
pounds, but  tests  have  been  devised  which  allow  the 
relative  power  to  be  compared.  Comparisons  should, 
however,  only  be  made  between  explosives  of  a  similar 
nature,  as  the  figures  given  for  brisant  and  non-brisant 


EXPLOSIVE  PROPERTIES  179 

explosives  are  hardly  comparable.  Useful  as  these  com- 
parisons are,  it  should  always  be  borne  in  mind  that  the  best 
test  of  an  explosive  is  its  behaviour  under  working  con- 
ditions, and  it  is  practically  impossible  to  imitate  these. 
There  are  three  methods  in  general  use  for  testing  power, 
viz.  the  Trauzl  lead  block  test,  the  mortar  test,  and  the 
ballistic  pendulum.  Of  these  the  Trauzl  lead  block  is  the 
simplest,  and  is  the  most  generally  used  on  the  Continent, 
whereas  the  ballistic  pendulum  is  the  most  elaborate  and 
probably  the  best.  A  ballistic  pendulum,  however,  is  an 
expensive  piece  of  apparatus,  so  that  its  use  is  practically 
limited  to  the  official  testing  of  explosives  for  the  British 
Permitted  L,ist  or  the  United  States  L,ist  of  Permissible 
Explosives. 

Trauzl  Lead  Block. — This  test  is  based  on  the  volume 
of  the  cavity  formed  when  a  given  weight  of  an  explosive 
is  fired  in  a  bore-hole  made  in  a  block  of  pure  lead,  and  in 
order  to  obtain  comparable  results  the  test  must  be  carried 
out  under  absolutely  standard  conditions.  These  conditions 
have  been  defined  by  a  committee  appointed  by  the  Inter- 
national Congress  of  Applied  Chemistry  (V.  Congress,  1903, 
vol.  ii.  p.  256),  and  may  be  summarized  as  follows : — 

The  blocks  are  circular  in  section,  and  are  20  cm.  high 
and  20  cm.  in  diameter.  They  are  cast  of  pure,  soft  chemical 
lead,  the  bore-hole,  which  is  125  mm.  deep  and  25  mm.  in 
diameter  being  situated  in  the  centre  and  cast  in  by  means 
of  a  suitable  mould.  Before  use  the  blocks  are  allowed  to 
stand  for  several  days.  The  weight  of  the  explosive  used  is 
10  grams,  and  this  is  made  up  into  a  cartridge  25  mm.  in 
diameter  by  wrapping  it  in  a  piece  of  tinfoil  70  mm.  wide, 
the  length  of  the  long  sides  being  120  and  150  mm.  The 
foil  is  of  such  a  thickness  that  I  square  metre  weighs 
80-100  grams.  A  No.  8  electric  detonator  is  inserted  into 
the  cartridge,  and  the  cartridge  then  pressed  to  the  bottom  of 
the  hole  with  a  wooden  rod,  the  wires  being  kept  central. 
Tamping  is  then  applied  by  filling  the  hole  with  sharp,  dry 
quartz  sand,  which  is  of  such  a  degree  of  fineness  that  it 
passes  a  sieve  with  144  meshes  per  cm.2,  the  wires  being 


i8o 


EXPLOSIVES 


•35  mm.  thick.  The  charge  is  then  fired  electrically,  and 
any  residue  left  shaken  and  brushed  out  of  the  cavity. 
The  volume  of  water  required  to  fill  the  cavity  is  then 
determined,  and  the  volume  of  the  original  bore-hole 
deducted,  the  figure  thus  obtained  being  taken  as  a  measure 
of  the  power  of  the  explosive.  At  least  three  tests  should 
be  made,  and  the  mean  of  the  figures  thus  obtained  com- 
pared with  the  mean  of  three  similar  tests  made  with  a 
standard  explosive  of  approximately  the  same  velocity  of 
detonation.  The  test  should  be  carried  out  at  a  tem- 
perature of  I5°-20°  C.  The  enlargement  caused  by  a  de- 
tonator alone  is  sometimes  determined  in  the  same  way, 


FIG.  26. — Trauzl  Block 
before  Firing. 


FIG.  27. — Trauzl  Block 
after  Firing. 


and  this  value  deducted,  but  as  the  test  is  only  a  comparative 
one  this  is  unnecessary  provided  the  standard  explosive  is 
fired  with  a  detonator  of  the  same  strength.  Figs.  26  and 
27  show  Trauzl  blocks  in  section  before  and  after  firing. 

The  Trauzl  block  test  is  a  convenient  one,  but  suffers 
from  several  uncertainties.  In  the  first  place,  it  fails  with 
non-detonating  explosives,  as  the  pressure  is  developed  so 
slowly  that  the  tamping  is  blown  out.  In  the  second  place, 
it  is  affected  by  variations  in  the  lead  and  in  the  sand  used 
for  stemming,  so  that  as  large  a  number  of  blocks  as  possible 
should  be  cast  from  one  melt  and  a  good  stock  of  sand  kept. 
With  aluminium  explosives,  and  other  explosives  with  a 


EXPLOSIVE  PROPERTIES  181 

very  high  temperature  of  explosion,  high  results  are  obtained 
owing  to  erosion,  whereas  with  explosives  containing  an 
excess  of  oxygen  the  influence  of  the  tinfoil  wrapper  comes 
into  play  unless  the  standard  explosive  used  also  contains 
a  similar  excess  of  oxygen.  The  weight  of  the  wrapper  is 
about  i  gram,  i.e.  10  per  cent,  of  the  weight  of  the  explosive. 
The  following  table  gives  a  few  characteristic  results 
obtained  when  explosives  are  fired  in  the  lead  block  :— 

N.G.           . .          . .     540  cc.  P.A.     . .  297  cc. 

B.G 530  cc.  T.N.T. . .  254  cc. 

Dynamite  No.  i   . .     300  cc.  Tetryl  . .  375  cc. 

65  N.G.     ) 

Gelignite ]  25  NaNO3>  420  cc.  G.C.      ..  290  cc. 
18  W.M.      j 

Mortar. — This  is  shown  in  Fig.  28,  the  test  being  carried 
out  by  measuring  the  distance  that  the  shot  is  thrown  when 


FIG.  28. — Mortar. 


10  grams  of  the  explosive  are  fired. ,  The  explosive  is  weighed 
out  in  a  wooden  shell  30  mm.  in  external  diameter  and  60  mm. 
deep,  which  is  then  inserted  into  the  charge  chamber.  A 
piece  of  safety  fuze  with  a  detonator  at  one  end  is  passed 
through  the  central  hole  in  the  shot,  and  the  shot  then  placed 
in  position  with  the  detonator  pushed  well  down  into  the 
explosive.  The  shot  weighs  15  kilos,  and  should  be  a  good 


i82  EXPLOSIVES 

but  not  a  tight  fit  in  the  gun.  The  gun  is  securely  fixed 
on  a  concrete  foundation,  and  is  usually  set  with  its  axis 
at  an  elevation  of  45°.  The  distance  that  the  projectile 
is  thrown  is  measured  and  compared  with  that  obtained 
with  an  equal  weight  of  a  standard  explosive  of  the  same 
nature.  The  bore  at  the  back  of  the  gun  is  provided  so  that 
when  one  end  becomes  worn  out  the  gun  can  be  turned. 

The  method  is  a  Somewhat  crude  one,  but  gives  more 
constant  results  than  one  would  expect,  and  is  useful  when 
experimenting  with  new  explosive  mixtures.  In  order  to 
obtain  reliable  results  at  least  three  shots  should  be  fired, 
and  it  is  advisable  also  to  fire  one  or  two  clearing  shots 
first  in  order  to  free  the  gun  from  rust.  When  new  the 
projectiles  are  inclined  to  expand  in  diameter  owing  to  the 
shock  of  the  explosions,  and  give  unreliable  results,  but  this 
expansion  ceases  after  a  few  shots  have  been  fired.  In 
order  to  make  a  gas-tight  joint  the  shot  should  be  well  lubri- 
cated before  being  inserted.  The  following  figures  give  an 
idea  of  the  average  throw  obtained  with  a  few  standard 
explosives,  a  15  kg.  shot  being  used,  and  the  gun  being  set 
at  an  angle  of  45°  : — 

Blasting  Gelatine 240  metres 

Gelatine  Dynamite          . .          . .  188 

Gelignite 168 

Dynamite  No.  i  . .         . .          . .  132       ,, 

The  explosives  on  the  British  Permitted  lyist  give 
throws  usually  varying  between  80  and  120  metres. 

In  order  to  save  the  trouble  of  fetching  the  projectile 
after  each  shot,  the  gun  is  sometimes  mounted  as  a  pendulum 
and  the  shot  fired  into  a  sand  bank  a  few  feet  away.  In 
this  case  the  recoil  is  measured,  the  arrangement  being  very 
similar  to  that  of  the  ballistic  pendulum  described  below. 

The  Ballistic  Pendulum.— This  is  the  Official  Test  for 
the  power  of  coal  mine  explosives  both  in  the  United  States 
and  in  this  country,  and  both  pendulums  will  be  described. 
The  test  has  the  great  advantage  that  a  reasonable  weight 
of  explosive  is  used,  J  Ib.  in  America  and  \  Ib.  in  this  country, 


EXPLOSIVE   PROPERTIES  183 

and  that  it  is  fired  in  its  original  wrapper  and  hence  all 
wrapper  influence  is  eliminated,  or,  rather,  the  wrapper 
influence  is  much  the  same  as  it  would  be  under  working 
conditions. 

The  pendulum  at  the  U.S.A.  testing  station  at  Pittsburg 
consists  of  a  12*2  in.  U.S.A.  Army  mortar,  weighing  31,600 
Ibs.  It  is  slung  in  a  stirrup  made  of  ij-in.  machine  steel 
rod,  the  rods  being  8g|  in.  long.  It  is  suspended  on  nickel 
steel  knife  edges  working  on  nickel  steel  bed  plates,  the  bed 
plates  resting  on  massive  concrete  pillars.  The  explosive 
is  loaded  into  a  steel  gun  which  runs  on  a  30-in.  gauge  track 
and  is  tamped  with  one  pound  of  clay,  or  two  pounds  when 
slow  burning  non-detonating  explosives  such  as  gunpowder 
are  being  tested.  Before  firing  the  gun  is  run  up  to  the 
mortar  until  exactly  ^  in.  away  from  it. 

The  charge  of  standard  explosive  is  eight  ounces  of  40  per 
cent.  American  Straight  Dynamite  of  the  composition — 

N.G 40 

NaNO3 44 

W.M 15 

CaCO3       i 

which  gives  a  swing  of  27-3*1  in.  By  means  of  trial  and 
failure  the  weight  of  the  explosive  that  gives  approximately 
the  same  swing  as  this  is  then  determined,  and  three  shots 
fired  with  this  weight.  The  exact  equivalent  is  then 
calculated  from  the  ratio — 

S, :  SD  =  W  f  i 

where  S*  =  swing  given  by  W  Ib.  of  the  explosive  under  test, 

SD  =  swing  given  by  J  Ib.  of  the  standard  explosive. 
The  pendulum  in  use  at  the  British  testing  station  at 
Rotherham  is  somewhat  smaller.  The  pendulum  itself  is  a 
mortar  weighing  5  tons  and  suspended  by  steel  rods  from 
an  overhead  axle  having  roller  bearings.  The  bore-hole  of 
the  gun  is  30  in.  long  and  if  in.  diameter,  and  the  gun  is 
placed  2  in.  from  the  mortar.  Two  pounds  of  well-rammed 
dry  clay  are  used  as  stemming,  and  the  charge  of  explosive 


184 


EXPLOSIVES 


used  is  four  ounces.  The  swing  given  is  read  off  and  com- 
pared with  the  swing  given  by  four  ounces  of  Gelignite 
containing  60  per  cent,  of  nitroglycerine,  this  swing  being 
3*27  in.  The  swings  recorded  by  the  most  important 
explosives  on  the  Permitted  lyist  are  given  in  Section  V. 

TESTS  FOR  VIOLENCE 

By  the  violence  or  brisance  of  an  explosive  is  meant  the 
shattering  effect  produced.  This  is  rather  an  illusive 
quantity  and  depends  not  only  on  the  power  but  also  on 
the  maximum  pressure  developed,  this  in  turn  depending 
on  the  velocity  of  detonation.  Proposals  have  been  made  to 
calculate  the  brisance  mathematically,  Bichel  giving  the 
formula  |MV2  where  M  is  the  mass  of  the  gaseous  products 

and  V  the  velocity  of  detonation. 
These,  and  other  similar  expressions, 
however,  do  not  give  a  satisfactory 
value,  and  attempts  have  been  made 
to  determine  the  comparative  bri- 
sance experimentally.  The  results 
obtained  cannot  be  said  to  be  very 
satisfactory  so  far,  but  they  do  give 
some  idea  of  the  relative  brisance. 
They  are  all  based  on  the  crusher 
gauge  principle  and  measure  the 
deformation  of  a  cylinder  of  a  soft 
metal,  such  as  copper  or  lead.  The 
best-known  form  of  apparatus  is 
the  brisance  meter  devised  by  Kast 
and  shown  in  section  in  Fig.  29.  This  consists  of  a 
hollow  steel  cylinder  resting  on  a  heavy  steel  base.  A 
small  copper  cylinder  is  placed  centrally  on  the  base,  and 
on  the  top  of  this  a  heavy  steel  piston  which  is  an  accurate 
fit  in  the  steel  cylinder.  On  the  top  of  the  piston  is  placed 
a  nickel  steel  plate  20  mm.  thick  and  weighing  320  grams, 
on  which  rest  two  4  mm.  lead  discs.  These  lead  discs  are 
renewed  after  each  shot,  and  have  the  object  of  protecting 
the  steel  plate.  The  explosive  is  fired  on  the  top  of  them, 


FIG.  29. — Brisance  Meter. 


EXPLOSIVE  PROPERTIES 


185 


and  the  crushing  of  the  copper  cylinder  taken  as  a  measure 
of  its  brisance.  The  figures  obtained  vary  with  the  diameter 
and  length  of  the  cartridges,  and  seem  to  be  at  a  maximum 
when  the  length  of  the  cartridge  is  about  four  times  its 
diameter.  As  would  be  expected,  they  also  vary  with  the 
density  of  the  explosive,  this  having  a  great  effect  on  the 
velocity  of  detonation.  As  the  explosive  is  fired  unconfined, 
the  test  does  not  in  any  way  represent  the  conditions 
attained  in  practical  blasting  operations.  The  following 
figures  were  obtained  using  15  grams  of  the  explosive  in 
the  form  of  a  cartridge  21  mm.  in  diameter  : — 


Explosive. 

Density. 

Velocity  of 
detonation. 

Brisance. 

( 

1-42 

. 

3'  5  7 

Tetryl      J 

i'53 

7145 

3'9I 

1*59 

7160 

3*94 

i'34 

6l6o 

2-81 

Picric  Acid 

1-40 
1*53 

6700 
7000 

3'34 
3'55 

I  -60 

7100 

3-88 

i'34 

594° 

2'8o 

T.N.T  

i'45 

6400 

2'93 

1-50 

6590 

3-13 

1-60 

6680 

3'I3 

D.N.B  

'93 

— 

r6i 

/T.N.T.  30        ..          ..   / 
\Pb(N03)27o    ..         ..  t 

2-65 

2'75 

4600 
4700 

2-52 
2-86 

VELOCITY  OF  DETONATION 

The  velocity  of  detonation  represents  the  speed  at  which 
detonation  spreads  or  travels  throughout  the  mass  of  the 
explosive  when  once  initiated.  It  can  be  determined  by 
two  methods,  viz.  by  the  absolute  method,  in  which  the 
interval  of  time  is  actually  measured,  and  by  the  compara- 
tive method,  in  which  the  velocity  of  detonation  of  one  ex- 
plosive is  measured  relatively  to  the  velocity  of  detonation 
of  another. 

Owing  to  the  high  velocities  attained,  frequently  6000- 
8000  metres  per  second,  the  absolute  method  resolves  itself 
into  the  problem  of  measuring  very  small  intervals  of  time. 


i86 


EXPLOSIVES 


For  example,  if  a  train  of  cartridges  of  Blasting  Gelatine 
10  metres  long  is  detonated  at  one  end,  the  detonation  has 
reached  the  other  end  in  about  -0013  second.  For  accurately 
measuring  such  very  short  intervals  of  time  the  best  method 
has  been  found  to  be  a  drum  of  known  diameter  rotating 
at  a  known  speed.  From  the  speed  of  rotation  and 
diameter  of  the  drum  the  linear  velocity  of  any  point  on 
the  surface  is  readily  calculated,  and  hence  the  time  that 


FIG.  30. — Determination  of  Velocity  of  Detonation  (Mettegang's  Direct 

Method). 

has  elapsed  between  the  making  of  two  marks  can  be  deduced. 
The  Mettegang  time  recorder  for  the  determination  of 
velocity  of  detonation  is  based  on  this  principle  and  by  its 
use  intervals  of  time  down  to  i  x  io~7  seconds  can  be 
measured.  The  arrangement  of  the  apparatus  is  shown 
diagrammatically  in  Fig.  30.  Two  thin  wires  are  embedded 
in  the  explosive  under  test  at  a  suitable  distance  apart, 
usually  about  3-4  metres,  each  of  these  wires  forming  part 


EXPLOSIVE   PROPERTIES  187 

of  the  primary  circuit  of  different  induction  coils.  One 
terminal  of  the  secondary  circuit  of  each  of  these  coils  is 
connected  with  the  axis  of  the  drum,  while  the  other  terminal 
is  connected  with  a  platinum  point  which  nearly,  but  not 
quite,  touches  the  smoked  surface  of  the  drum.  The  drum 
is  rotated  by  an  electric  motor  at  such  a  speed  that  the  linear 
velocity  of  the  surface  is  100  metres  per  second,  and  the 
explosive  is  then  detonated.  When  the  detonation  reaches 
the  first  wire  it  breaks  the  primary  circuit  in  one  of  the  coils, 
and  the  current  thereby  induced  in  the  secondary  circuit 
causes  a  spark  to  pass  between  the  corresponding  platinum 
point  and  the  drum,  this  spark  leaving  a  mark  on  the  smoked 
surface.  The  same  thing  takes  place  when  the  detonation 
reaches  the  second  wire,  and  by  measuring  the  distance 
between  the  two  marks  the  time  taken  for  the  detonation 
to  travel  between  the  two  wires  is  calculated.  The  distance 
between  the  two  marks  on  the  drum  is  measured  by  a 
travelling  microscope  with  a  vernier  scale  reading  to  -01  mm., 
this  corresponding  to  ixio"7  seconds  when  the  surface 
velocity  of  the  drum  is  100  metres  per  second.  By  using 
more  wires,  each  wire  being  connected  with  a  separate  coil 
and  platinum  point,  measurements  of  the  velocity  of  detona- 
tion at  different  points  in  a  long  train  of  cartridges  can  be 
determined,  thus  ascertaining  in  any  given  case  whether  the 
velocity  remains  constant  or  whether  it  increases  or 
decreases. 

A  certain  amount  of  time  always  elapses  between  the 
breaking  of  the  primary  circuit  and  the  passing  of  the  spark 
due  to  the  induced  current  in  the  secondary  circuit.  In 
order  to  eliminate  error  from  this  source  by  making  the  lag 
the  same  in  both  cases,  the  strength  of  the  current  in  both 
primary  circuits  must  be  the  same,  the  coils  must  be  of 
exactly  similar  construction  and  resistance,  and  the  direction 
of  the  flow  of  the  current  must  be  the  same  in  both. 

In  the  indirect  method  the  velocity  of  detonation  of  the 
explosive  is  measured  in  terms  of  the  velocity  of  detonation 
of  another  explosive,  detonating  fuze  always  being  chosen  for 
purposes  of  comparison  owing  to  its  convenience  and  very 


i88 


EXPLOSIVES 


constant  velocity,  about  5000  metres  per  second.  The 
determination  is  a  very  simple  one,  the  arrangement  used 
being  shown  in  Fig.  31.  Two  detonators  are  inserted  into 
the  cartridge  under  test  at  a  measured  distance  apart, 
10  cm.  being  sufficient.  Bach  detonator  is  connected  to 
one  end  of  a  length  of  detonating  fuze,  the  centre  of  which 
rests  on  a  lead  plate.  A  mark  is  made  on  the  lead  plate 
corresponding  with  the  middle  of  the  length  of  fuze,  and 
the  cartridge  of  explosive  then  fired  by  means  of  an  electric 
detonator  inserted  in  one  end.  When  the  detonation  reaches 
the  first  detonator  it  detonates  one  end  of  the  fuze,  and  when 
it  reaches  the  other  detonator  it  detonates  the  other  end  of 


-\ 


FIG.  31. — Determination  of  Velocity  of  Detonation  (Indirect  Method). 

the  fuze.  These  two  waves  of  detonation  travelling  through 
the  fuze  in  opposite  directions  meet  at  a  certain  point,  and 
where  this  happens  a  mark  is  left  on  the  lead  plate.  Ob- 
viously the  distance  of  this  mark  from  the  centre  of  the 
fuze  represents  the  start  that  the  one  wave  of  detonation 
had  over  the  other  wave,  and  hence  the  velocity  of  detonation 
of  the  explosive  can  be  calculated  in  terms  of  the  velocity  of 
detonation  of  the  fuze. 

The  velocity  of  detonation  is  affected  to  some  extent  by 
the  diameter  of  the  cartridge,  and  increases  as  the  diameter 
increases.  It  usually,  however,  reaches  a  limiting  value 
above  which  it  remains  constant  however  much  the  diameter 
is  increased.  With  pure  nitroaromatic  compounds  maximum 


EXPLOSIVE  PROPERTIES  189 

velocity  is  reached  at  10  mm.,  but  with  other  explosives  it  is 
somewhat  more,  usually  about  30  mm.,  and  in  the  case  of 
ammonium  nitrate  explosives  is  frequently  over  50  mm. 
The  following  figures  serve  to  illustrate  this  point : — 

Diameter        Velocity 
Explosive.  (mm.),      (metres  per  sec.). 

Pure  cast  T.N.T.             . .          . .  21  6700 

0  =  1-58 75  6595 

220  6675 

300  6710 


Aldorfit 


AmNO3  =  81  . .         . .       — 

T.N.T.    =  17  . .         . .       26  4430 

Rye  meal    2  . .         . .       40  49^5 


The  strength  of  the  detonator  or  primer  has  little  or  no 
effect  provided  it  is  sufficiently  strong,  but  very  irregular 
results  are  sometimes  obtained  at  first,  both  abnormally 
high  and  low.  With  most  explosives  the  velocity  of  the 
wave  of  detonation  increases  or  decreases  until  its  normal 
value  is  reached  and  then  remains  constant,  but  insensitive 
ammonium  nitrate  explosives  behave  in  a  somewhat  different 
way,  the  velocity  gradually  decreasing.  This  is  probably 
due  to  insensitiveness,  as  the  effect  is  most  marked  when  the 
explosive  is  compressed  to  a  high  density,  in  which  case 
detonation  is  usually  difficult  to  start.  lowering  the 
temperature,  on  the  other  hand,  has  no  effect,  velocities 
remaining  constant  even  at  the  temperature  of  liquid  air 
(-180°  C.). 

The  effect  of  compressing  the  explosive  and  thus  raising 
its  density  is  very  great,  and  experiments  seem  to  demonstrate 
that  velocity  of  detonation  is  a  linear  function  of  density. 
It  is  true  that  with  Cheddite  and  some  other  explosives  the 
velocity  falls  if  the  density  exceeds  a  certain  figure,  but  this 
is  probably  due  to  the  difficulty  in  starting  a  satisfactory 
wave  of  detonation  owing  to  the  diminished  sensitiveness 
of  the  explosive.  Thus  picric  acid  enclosed  in  paper 
cartridges  20  mm.  in  diameter  gave  the  following  figures 
when  fired  with  a  detonator  consisting  of  *5  gram 


EXPLOSIVES 

fulminate  and  a  primer  containing  25  grams  of  Dynamite 
No.  i— 

Density.  Velocity. 

'93  ..........      5035 

I-3I  ..........      6255 

1-46  ..........      6988 

I'67  ..........      7277 

171  ..........      5045 

174  ..........     Failed 

By  increasing  the  primer  charge  to  80  grams  of  Dynamite 
picric  acid  gave  the  following  figures  :  — 

Density.  Velocity. 

1-62  .........  .     737° 

172  ..........     749° 

173  ..........     7645 

174  ........     7645 

showing  that  by  increasing  the  initial  shock  the  explosive 
could  still  be  detonated  and  that  the  velocity  of  detonation 
continued  to  increase. 

Very  similar  results  were  obtained  with  T.N.T.  — 

Density.  Detonator.  Primer.  Velocity. 

•84  '5  gram  fulminate               Nil                   3822 

•91  »                             »                     4087 

•92  „                             „                     4*7° 

•90  ,,         25  grms.  Dynamite  No.  i  4170 

•91  »  »  4170 

1-32  „  »  62i7 

1-46  „  »  6675 

1-56  ,,  „  6880 

i'59  „  »  7056 

i  -60  „  «  7J4° 

1-605  „  „  Failed 

1-61  „         80  grms.  Dynamite  No.  i  6943 


The  last  figure  was  obtained  when  the  T.N.T.  was  con- 
fined in  a  copper  tube,  whereas  the  others  were  obtained 
when  the  explosive  was  confined  in  paper. 


EXPLOSIVE  PROPERTIES  191 

The  influence  of  the  degree  of  confinement  is  very  slight 
with  sensitive  explosives  having  a  high  velocity  of  detona- 
tion, but  with  the  insensitive  explosives  of  the  ammonium 
nitrate  class  it  is  very  considerable.  Figures  illustrating 
this  will  be  found  on  pages  194  and  195. 

Nitroglycerine  exhibits  the  peculiarity  of  having  two 
velocities  of  detonation,  one  about  1300-1500  metres  per 
second,  and  the  other  about  7000-9000  metres  per  second. 
At  which  of  these  velocities  the  wave  of  detonation  travels 
depends  a  good  deal  on  the  diameter  of  the  tube  and  on 
the  strength  of  the  primer  or  detonator,  the  following  results 
having  been  recorded  : — 

Detonator. 

i '6  grams. 
1-6 


Primer.              Diameter. 

Velocity. 

6  mm.  (glass) 

Failed 

9  mm.  (glass) 

654 

25  mm.  (iron) 

1441  and  7690 

38  mm.  (iron) 

8527 

— 

1776 

Detonating  38  mm.  (iron) 

7234 

fuze 

Interesting  results  of  the  same  nature  have  been  obtained 
with  various  American  Dynamites  and  gelatinized  explosives. 
These  latter  when  fired  with  a  detonator  only  have  a  velocity 
of  detonation  of  about  2300  metres  per  second  and  this  figure 
is  scarcely  altered  by  increasing  or  decreasing  the  amount  of 
nitroglycerine  present.  When  fired  with  a  primer  of  American 
Straight  Dynamite,  however,  the  velocity  is  much  greater 
and  increases  with  the  percentage  of  nitroglycerine,  being 
about  5100  metres  per  second  with  a  nitroglycerine  content 
of  40  per  cent.,  6600  metres  with  Gelignite  containing  60  per 
cent,  of  nitroglycerine,  and  7000  metres  with  75  per  cent. 
Gelatine  Dynamite.  With  the  Straight  Dynamites,  on  the 
other  hand,  the  velocity  of  detonation  increases  regularly 
with  increasing  nitroglycerine  content,  and  is  not  affected 
by  the  use  of  a  primer,  provided  a  detonator  of  suitable 
strength  is  used. 


IQ2 


EXPLOSIVES 

AMERICAN  DYNAMITES 


Gelatines. 

Per  cent.  N.G. 

Straight  Dynamites  with 
or  without  Primer. 

Detonator  only. 

Detonator  and  Primer. 

5 

1294 



_ 

10 

2103 

— 

— 

15 

3°95 

— 

—  • 

20 

3197 

— 

— 

25 

3296 

—  . 

— 

30 

4172 

2484 

— 

35 

4605 

2278 

— 

40 

4848 

2230 

5122 

45 

5°32 

2279 

5544 

50 

5348 

2355 

5862 

60 

5973 

2104 

6606 

75 

6265 

2165 

6999 

With  Ammonia  Dynamite  in  which  half  the  nitroglycerine 
has  been  replaced  by  ammonium  nitrate  the  velocity  of 
detonation  increases  from  2100  with  the  10  per  cent,  grade 
to  about  4400  with  the  45  per  cent,  grade  and  thereafter 
falls,  the  60  per  cent,  grade  giving  a  velocity  of  3000.  These 
explosives  are  not  gelatinized,  and  the  velocity  is  not 
materially  increased  by  the  use  of  a  primer.  Obviously  the 
increase  in  velocity  shown  when  passing  from  grade  10  to 
grade  45  is  due  to  the  increasing  nitroglycerine  content, 
whereas  beyond  45  per  cent,  the  ammonium  nitrate  content 
becomes  the  predominating  influence,  ammonium  nitrate 
explosives  always  being  slow. 

The  dual  velocity  of  detonation  exhibited  by  liquid 
nitroglycerine  and  gelatinized  explosives  is  probably  to  be 
accounted  for  by  their  exhibiting  dual  elasticity,  under  a 
light  shock  behaving  as  liquids  and  under  a  heavy  shock 
as  solids.  The  velocity  of  sound  depends  on  the  modulus 
of  elasticity  of  the  transmitting  medium  according  to  the 
equation  — 


where  \L  is    Young's    modulus    and  d   the    density,    and 
probably  the  velocity  of  detonation  follows  a  similar  law, 


EXPLOSIVE  PROPERTIES 


193 


but  no  results  seem  to  have  been  recorded  in  which  the 
modulus  has  been  determined.  Certainly  the  velocity  of 
detonation  increases  with  the  density  instead  of  decreasing, 
but  no  conclusions  can  be  drawn  from  this  fact  until  the 
effect  of  increasing  density  on  elasticity  has  been  studied  ; 
for  if  the  modulus  increases  more  rapidly  than  the  density, 
then  the  velocity  of  detonation  would  also  increase  if  it 
followed  the  above  equation.  The  following  table  gives  the 
velocity  of  detonation  in  metres  per  second  of  a  few  well- 
known  explosives,  where  irregular  results  have  been  obtained, 
the  mean  of  the  most  concordant  figures  being  given : — 


Explosive. 

Density. 

Velocity. 

Remarks. 

Mercury  Fulminate 
Detonating  fuze  .  . 

— 

3920 
5000-6000 

6-45  mm.  diam. 
Phlegmatized  fulmin- 

ate. 

1*5 

4800-5000 

T.N.T.  4-4  mm.  diam. 

Guncotton,  dry   .  . 

'9 

3900 

— 

,, 

'2 

4300 

— 

,,                  .  . 

'4 

4800-6200 

— 

wet   (15  per\ 
cent.  H20)J 

— 

5500-5800 

23  mm.  diam. 

Nitromannitol     .  . 

*5 

7000 

4 

. 

'9 

7700 

Nitroglycerine 



1440  and  7690 

25 

Tetryl       
Picric  acid 

i'5 

•34 

7200 
6160 

21 

,, 

•46 

6700 

» 

'53 

7000 

•60 

7100 

Trinitrochlorbenzole 

•66 

6800 

Hexanitrodiphenylamine 

i'5 

8-1-67 

7125 

Trinitrocresol 

•52 

6620 

. 

•62 

6850 

Trinitro  benzole     (1.3.5) 

•63 

6850 

Trinitrotoluol  (2.4.6)  .  . 

'34 

594° 

'45 

6400 

p 

'5° 

6590 

•60 

6680 

Dinitrobenzole  (1-3) 

'5° 

6000 

Macaritej™^;; 

2'73 
2-89 

4695 
4860 

£e£^6337}  compressed  '  ' 

1-58 

6965 

„        7155* 

T-N.T.  90|compressedt> 

1-56 

6725 

,,        6680* 

a$:SH-.    - 

i-57 

6565 

„        6680* 

*  These  figures  refer  to  the  velocity  of  detonation  of  the  chief  con- 
stituent of  the  mixture  at  the  same  density. 

T.  13 


194 


EXPLOSIVES 


Explosive. 

Density. 

Velocity. 

Remarks. 

j^  XT  V       \  compressed  .  . 

i-53 

6280 

21  mm.  diam. 

6660* 

T.N.T.  50! 

(         1480 

\ 

D.N.T.  5ojcast  " 

I'5I 

"((Incomplete) 

}       "          " 

T.N.T.  5o\ 

/        1910 

D.N.T.  50)  c        '  ' 

J*53 

\  (Incomplete) 

" 

T  N.T.  99'5)                    A 

(       '3° 

Failed 

26    ,, 

Soft  wax  .2jcomPr€ 

I      '33 

5515 

,, 

5920* 

Dynamite  No.  i^  ?55 

•63 

1990 
2560 

20     ,, 

M 

'34 

3670 

,,             ,, 

99 

*54 

5230 

»             » 

It 

•62 

6800 

,, 

Blasting  Gelatine^  ~J$*        1-63 

7700 

30    .. 

fN.G.  62 

Gelignite!  ^0,27      !'  !      1-67 

2055 
7000 

26    „ 

3°    >• 

I  W.M.  8 

N.G.  50..   ! 

Dynamite,        KNO^ri 
5opercent.  WM39.? 

1-56 

4610 

26    , 

CaCO3  '2 

!N.G.  40  .  . 

NaNO3  42 
W.M.  16-7 

1-56 

444° 

»•          i  > 

CaCO3  1-2 

!N.G.  35      .'. 

C.C.  -3        -. 

Ba(NO3)2  4    i      1-13 

3970 

»          » 

KNO325'5            1-20 

4070 

» 

Tan  meal  34*8 

NaaC<V5.. 

rN.G.  30 

Carbonite]NaNO324-5  .  . 

3720 

»          » 

No.  II.  J  Flour  40-5     .. 

I'lO 

3850 

,,         ,, 

lK2Cr2075     .- 

• 

IN.G.  30       .  . 

Flo'u?™1  '  ' 

- 

W.M.  6        !'. 

ri6 

3900 

„ 

Naphthalene  •* 

Alum  i 

N.G.  3*8 

C.C.  "2 

•89 

3700 

26mm.diam.confined. 

Donarite  AmNO8  80     .  . 

1-31 

4140 

3° 

T.N.T.  12 

1-31 

393° 

,,     unconfined. 

Flour  4 

rN.G.  4        ..         ro6 

3385 

40  mm.  diam. 

Ammon-      lAmNO382            1-23 
Carbonite]  KNO3  10    ..         1-19 

3315 
1650 

26        „ 
30        ,,     unconfined. 

(Flour  4       .  .   j      1*19 

3100 

30         ,,         confined, 

*  These  figures  refer  to  the  velocity  of  detonation  of  the  chief  con 
stituent  of  the  mixture  at  the  same  density. 


EXPLOSIVE  PROPERTIES 


195 


Explosive. 

Density. 

Velocity. 

Remarks. 

Aldorfit! 

AmNO3  81 
T.N.T.  17 
Rye  flour  2 

I'l 

•14 
•16 

4825 
4410 

4925 

40  mm.  diam.  confined. 
26 

4° 

I 

•17 

4960 

5° 

AmNO3  66       .  . 

•10 

394° 

26 

Gesteins 
Dorfit 

T.N.T.  15 
KN03  5 

•ii 

4420 
4045 

40 
26 

NaCl  10 

•15 

45°5 

4° 

Rye  flour  5 

4605 

50 

(AmN0892.. 
Thunderite{T.N.T.  4     .  . 
(  Flour  4 

3650 
2137 

30 
3<> 

n 

unconfined. 

/AmNOo  42-5 

T.N.T.  10     .  . 
Permonite  KC1O4  32-5 
Starch  12 

1-05 
1-13 

3690 
3780 

4° 

mm.  diam. 

W.M.  3 

AmNO,  44-9 

Ammonal  (T.N.T.  31"    ..   ;      i'68 

4850 

21 

" 

The  velocity  of  detonation  of  Cheddite  was  given  on  page  no. 


PRESSURE  OF  EXPLOSION 

The  exceedingly  high  pressures  attained  during  ex- 
plosion render  exact  measurement  a  matter  of  considerable 
difficulty.  The  first  real  instrument  devised  to  estimate 
these  pressures  was  the  Rodman  gauge,  in  which  the  pressure 
drove  a  hardened  steel  knife  edge  into  a  soft  copper  disc, 
the  penetration  being  taken  as  a  measure  of  pressure 
attained.  The  design  of  this  gauge  was  afterwards  improved 
by  Nobel,  who  used  a  copper  cylinder  placed  between  a 
fixed  and  a  movable  steel  piston.  The  pressure  of  the 
gases  acting  on  the  base  of  the  movable  piston  crushed  the 
copper  cylinder,  from  the  deformation  of  which  the  pressure 
could  be  deduced.  This  type  of  gauge  is  known  from  its 
mode  of  action  as  the  crusher  gauge,  and  is  the  standard 
method  of  measuring  the  maximum  pressure  developed  by 
propellants  in  firearms.  When  used  for  this  purpose  the 
gauge  is  either  screwed  into  a  hole  bored  in  the  explosion 
chamber,  or  it  is  inserted  behind  the  cartridge,  so  that  the 
base  of  the  cartridge  is  in  contact  with  the  movable  piston. 


ig6  EXPLOSIVES 

This  latter  point  is  important,  as  otherwise  the  momentum 
of  the  cartridge  would  cause  abnormally  high  results.  For 
the  same  reason  the  movable  piston  must  be  closely  in 
contact  with  the  copper  cylinder,  and  when  the  gauge  is 
screwed  into  the  firearm  the  end  of  the  piston  on  which 
the  gases  act,  or  the  gas  check  which  is  usually  placed  in 
front  of  the  piston,  should  be  flush  with  the  end  of  the 
cylinder  in  which  the  piston  moves.  Otherwise  the  momen- 
tum of  the  gases  will  cause  abnormal  crushing. 

For  use  with  rifled  arms  in  which  the  maximum  pressure 
attained  is  about  15  tons  per  square  inch  copper  crushers 
are  always  used,  but  with  shot  guns  in  which  much  lower 
pressures,  viz.  about  3  tons  per  square  inch,  are  developed, 
lead  cylinders  are  frequently  employed.  The  use  of  the 
crusher  gauge  is  not,  of  course,  confined  to  the  study  of 
propellants,  but  can  be  used  for  the  study  of  blasting 
explosives  when  fired  in  bombs.  It  has  the  advantage  of 
being  inexpensive  and  convenient,  but  unfortunately  its 
use  is  limited  to  the  measurement  of  the  maximum  pressure 
attained,  and  it  gives  no  information  as  to  the  rate  of 
growth  of  this  pressure. 

Owing  to  the  extremely  rapid  rate  at  which  the  pressure 
rises  during  explosion,  records  showing  its  growth  are 
difficult  to  obtain,  and  although  one  or  two  instruments 
have  been  devised  for  the  purpose  their  use  is  limited,  and 
too  much  reliance  must  not  be  placed  on  the  results  obtained 
with  them.  One  of  the  most  satisfactory  is  the  Bichel 
recorder.  This  consists  of  a  massive  steel  cylinder,  the 
internal  dimensions  of  which  are  20  cm.  in  diameter  and 
48  cm.  deep,  the  capacity  thus  being  15  litres.  Charges 
of  100-200  grams  are  fired,  and  the  pressure  attained 
recorded  on  a  rapidly  revolving  drum  by  means  of  a  piston 
acting  against  a  powerful  spring.  The  shape  of  the  curve 
gives  a  qualitative  idea  of  the  rate  of  development  of 
pressure,  but  the  maximum  is  very  much  exaggerated 
owing  to  the  momentum  of  the  moving  parts.  By  neglect- 
ing this  peak  value  and  extending  the  curve  backwards 
by  extrapolation  until  it  cuts  the  ordinate  corresponding 


EXPLOSIVE  PROPERTIES  197 

to  the  moment  of  explosion  a  more  nearly  true  value  for 
the  maximum  pressure  can  be  read. 

Owing  to  the  low  density  of  loading  the  cooling  influence 
of  the  walls  is  very  great,  and  Bichel  has  sought  to  eliminate 
this  by  using  two  bombs,  one  of  20  litres  capacity  and  one 
of  15  litres  capacity.  By  means  of  inserting  metal  cylinders 
of  different  sizes  into  the  larger  of  these  he  was  able  to 
obtain  surfaces  of  3600,  6600,  and  7600  cm.2,  while  retaining 
the  same  volume  of  15  litres. 

On  firing  charges  under  these  three  conditions  he  ob- 
tained maximum  pressure  values  which  when  plotted  out 
against  the  area  were  found  to  lie  on  a  straight  line.  By 
extending  this  line  to  the  point  area=  o  the  pressure  with 
the  surface  eliminated  could  be  read  off.  More  recently 
Peteval  has  introduced  an  improved  recording  manometer 
in  which  a  very  stiff  spring  is  used,  and  consequently  only 
a  very  slight  movement  of  the  piston  takes  place,  this  being 
magnified  by  means  of  a  mirror  throwing  a  spot  of  light 
on  to  a  rapidly  moving  strip  of  sensitized  paper.  This 
recorder  has  been  used  for  the  study  of  propellants,  but  not 
for  high  explosives. 

HKAT  OF  EXPLOSION 

For  determining  the  heat  liberated  on  explosion  appara- 
tus similar  to  that  used  in  ordinary  calorimetric  work  is 
used,  but  with  suitable  modifications  to  enable  it  to  with- 
stand the  high  pressures  attained.  Two  types  of  bombs  are 
in  general  use,  viz.  the  comparatively  small  bomb,  the  walls 
of  which  are  very  thick  to  enable  it  to  withstand  the  high 
pressures  developed,  and  the  large  bomb  calorimeter  in  which 
the  increased  volume  results  in  lower  maximum  pressures, 
and  consequently  less  mechanical  strength  being  called 
for.  Berthelot  and  Sarrau  both  used  small,  light  bombs 
which  could  only  deal  with  a  few  grams  of  explosive  owing 
to  their  lack  of  mechanical  strength,  and  Nobel  and  Abel 
used  bombs  of  about  32  and  119  c.c.  capacity,  these  taking 
charges  of  12  and  26  grams  of  black  powder  respectively. 
Nobel,  however,  also  used  a  very  heavy  bomb  in  which  as 


198  EXPLOSIVES 

much  as  500  grams  of  black  powder  could  be  exploded, 
although  the  capacity  of  the  bomb  was  less  than  half  a 
litre.  It  is  very  difficult,  however,  to  construct  bombs  of 
this  type  suitable  for  dealing  with  large  charges  of  modern 
high  explosives,  although  a  nickel  steel  bomb  of  45  c.c. 
capacity  taking  a  charge  of  about  20  grams  has  been  used 
at  the  Neubabelsberg  testing  station,  and  is  said  to  give 
satisfactory  results. 

In  determining  the  heat  of  explosion  it  is  advisable  to 
use  large  quantities  of  the  explosive  in  order  to  reduce  the 
error  due  to  the  rather  uncertain  correction  which  has  to 
be  applied  to  eliminate  the  influence  of  the  detonator.  The 
uncertainty  of  this  correction  is  due  to  the  fact  that  the 
heat  liberated  by  a  detonator  depends  on  whether  it  is 
fired  in  an  atmosphere  rich  in  oxygen  or  not.  If  oxygen 
is  present  not  only  is  the  carbon  monoxide  liberated  by  the 
fulminate  burnt  to  carbon  dioxide,  but  the  copper  of  the 
detonator  case  is  oxidized  to  cupric  oxide,  and  heat  is  also 
liberated  by  the  combustion  of  the  electric  wires,  etc.,  the 
detonator  always  being  fired  electrically.  Thus  it  has 
been  found  that  a  No.  3  detonator  fired  in  the  absence  of 
oxygen  liberates  only  *ii6  Cal.  whereas  in  an  oxidizing 
atmosphere  it  liberates  791  Cal.,  and  the  amounts  are  of 
course  greater  with  larger  sizes.  In  order  to  obtain  a 
bomb  which  has  sufficient  mechanical  strength  to  withstand 
the  explosion  pressure  of  large  quantities  of  high  explosive 
without  undue  thickness  of  wall,  the  capacity  must  be 
increased.  This  has  been  done  by  Bichel  and  Mettegang, 
who  have  constructed  a  bottle-shaped  steel  bomb  with  a 
capacity  of  30  litres.  Its  walls  are  about  13  mm.  thick, 
and  it  weighs  some  70  kilos.  The  usual  charge  of  high 
explosive  used  is  100  grams,  but  in  the  case  of  black  powder 
more  than  double  this  amount  can  be  used  with  safety. 
All  the  usual  precautions  of  calorimetry  are  applied,  and  a 
thermometer  reading  to  '001°  C.  is  employed  for  observing 
the  rise  in  temperature,  as  on  account  of  the  large  heat 
capacity  of  the  metal  the  rise  in  temperature  of  the  sur- 
rounding water  is  only  about  i°  C. 


EXPLOSIVE  PROPERTIES 


199 


The  figures  thus  obtained  give  the  heat  evolved  when 
the  explosive  is  detonated  and  the  gases  cooled  to  the. 
ordinary  temperature,  and  therefore  include  the  heat 
evolved  by  secondary  reactions,  such  as  the  condensation 
of  the  greater  part  of  the  water  vapour  produced,  and  the 
heat  evolved  by  the  oxides  of  the  alkali  or  alkali  earth 
metals  combining  with  part  of  the  carbon  dioxide  produced 
to  form  bicarbonates.  Hence,  in  order  to  obtain  the  heat 
that  would  be  actually  evolved  under  practical  working 
conditions  corrections  must  be  applied.  The  following 
figures  give  the  heat  liberated  by  the  explosion  of  a  few 
well-known  explosives.  The  figures  refer  to  major  calories 
per  kilogram  of  explosive  : — 

Name.  Composition.          Heat  liberated. 

.TV- 
Dynamite  No.  i 

Blasting  Gelatine 


Gelignite 


Donarite 


Thunderite 


Carbonite 


Gunpowder     . . 

Nitroglycerine 
Ammonium  nitrate 
Mercury  Fulminate 


rN.G. 

75    ) 

IGuhr 

25      ' 

(N.G. 
*C.C. 

92    \ 
8    / 

/N.G. 
IC.C. 

6*'5\ 

\NaNO3 

IW.M. 

27-0  / 
8-oj 

/N.G. 

Q  *O\ 

C.C. 
T.N.T. 

I2'0\ 

AmNOg 

80*0 

\Flour 

4*O 

T.N.T. 

4 

AmNOg 

92 

Flour 

4 

N.G. 

25    ' 

KNOg 

30-5 

\ 


Ba(N03)2 
W.M. 


(KN03 
C. 

IS. 


1422 


1321 


836 


777 


576 


574 

1471 

365 
407 


20o  EXPLOSIVES 

Calorimetric  experiments  can  also  be  combined  with 
measurement  of  the  volume  of  gas  liberated.  This  can  be 
ascertained  by  direct  measurement,  but  the  large  volumes 
render  this  method  troublesome.  An  alternative  method 
is  to  weigh  the  calorimeter  before  and  after  allowing  the 
gas  to  escape,  and  then  calculating  the  volume  from  the 
weight  found  together  with  the  density.  More  usually, 
however,  the  pressure  is  measured  when  the  temperature 
has  become  constant,  and  the  volume  at  N.T.P.  then  calcu- 
lated by  the  laws  of  Boyle  and  Charles. 


TEMPERATURE  OF  EXPLOSION 

Very  little  is  known  of  the  temperatures  attained  by 
explosion,  and  no  attempts  seem  to  have  been  made  to 
measure  them  directly,  although  the  difficulties  of  doing 
so  by  means  of  an  optical  pyrometer  should  not  be 
insuperable,  this  method  having  been,  in  fact,  used  for 
testing  caps  (see  p.  152).  It  is  theoretically  possible  to 
calculate  the  temperature  attained  from  a  knowledge  of 
the  total  heat  liberated  and  the  specific  heats  and  latent 
heats  of  vaporization  of  the  products  of  explosion.  Un- 
fortunately two  factors  militate  against  the  accuracy  of 
such  calculations.  In  the  first  place,  nothing  is  known  of 
the  equilibrium  conditions  from  a  chemico-dynamic  point 
of  view  of  the  products  of  combustion.  It  is  fairly  certain 
that  at  the  high  temperatures  reached  both  carbon  dioxide 
and  water  are  to  a  large  extent  dissociated  into  their 
elements  — 

2C02  $  2CO  +  02  5>  2C  +  202 


and  probably  this  dissociation  to  some  extent  goes  a  step 
further,  molecular  oxygen  and  hydrogen  breaking  down 
into  the  monatomic  state.  In  all  the  above  cases  the  high 
pressure  attained  tends  to  force  the  equilibrium  to  the  left 
side  of  the  equation,  but  nothing  is  known  as  to  the  com- 
position of  the  equilibrium  mixtures  under  the  conditions 


EXPLOSIVE  PROPERTIES  201 

attained  during  or  immediately  after  explosion,  and  the 
same  applies  to  other  side  reactions,  such  as  the  temporary 
production  of  methane.  These  side  or  consecutive  reactions 
do  not,  of  course,  affect  the  total  heat  produced,  but  they 
do  affect  the  temperature  attained  by  causing  the  explosive 
reaction  to  take  place  over  a  greater  time.  In  other  words, 
side  and  consecutive  reactions  produce  a  lower  temperature, 
but  maintain  this  temperature  for  a  greater  time,  the  heat 
evolved  being  the  same  as  if  the  reaction  had  been  a  straight- 
forward one  taking  place  in  one  step. 

In  the  second  place,  the  specific  heats  of  gases  are  not 
even  approximately  constant  quantities,  but  increase  with 
increasing  temperature,  and  it  is  impossible  to  determine 
them  at  the  high  temperatures  attained  during  explosion, 
especially  as  these  temperatures  are  unknown.  Mallard 
and  I,e  Chatelier  have  investigated  the  matter,  and  have 
deduced  the  following  values  (minor  calories)  for  the 
molecular  heats  at  constant  volume  of  gases  at  temperature 
t°  C.  :— 

Permanent  gases,  such  as  N2,  O2,  H2  and  CO  4*80  +  -00062 
Easily  condensed  gases,  such  as  CO2  and  SO2  6*26  +  "0037^ 
Water  vapour  5-61  +  '0033^ 

and  other  investigators  have  obtained  similar  figures.  To 
what  extent  these  figures  are  accurate  it  is  difficult  to  say, 
but  it  is  improbable  that  their  accuracy  extends  beyond 
1500°  C.,  whereas  most  temperatures  of  explosion  are  pro- 
bably nearer  3000°  C.  The  values  of  Mallard  and  L,e  Chate- 
lier have,  however,  been  adopted  by  the  French  Government 
for  the  calculation  of  the  temperature  of  explosion  of  safety 
coal  mine  explosives.  The  calculation  is  a  somewhat 
cumbersome  one,  but  is  quite  straightforward,  and  as  the 
temperatures  of  explosion  of  explosives  for  use  in  coal 
seams  must  not  exceed  1500°  C.,  or  1900°  C.  in  the  case  of 
explosives  for  use  in  rock  in  coal  mines,  the  results  are 
probably  more  or  less  accurate,  at  all  events,  as  far  as  the 
former  are  concerned. 


202  EXPLOSIVES 

CHRONOGRAPHY 

In  the  case  of  propellants  the  velocity  imparted  to  the 
projectile  by  the  explosive  under  conditions  of  use  is  a  most 
important  point.  The  velocity  of  the  projectile  at  various 
points  in  its  trajectory  is  of  the  utmost  importance  in 
gunnery,  but  once  the  projectile  has  left  the  muzzle  the 
influence  of  the  propellant  ceases,  so  that  from  the  explosive 
manufacturer's  point  of  view  it  is  the  mean  muzzle  velocity, 
usually  abbreviated  to  M.M.V.,  that  matters.  The  name 
ballistics  is  given  to  the  study  of  the  flight  of  projectiles, 
internal  ballistics  dealing  with  their  behaviour  when  in  the 
barrel,  and  external  ballistics  dealing  with  their  flight  from 
muzzle  to  target.  The  subject  of  ballistics  is  highly  mathe- 
matical in  nature,  and  no  attempt  will  be  made  to  treat  it 
beyond  very  briefly  indicating  the  general  principles  on 
which  the  experimental  determination  of  velocity  is 
based. 

Instruments  for  determining  the  velocity  of  a  projectile 
are  known  as  chronographs,  and,  generally  speaking,  are  of 
two  types,  viz.  those  in  which  the  time  is  measured  in  terms 
of  the  time  taken  for  something  else  to  happen,  e.g.  in  the 
time  taken  for  a  weight  falling  freely  to  fall  a  certain  distance, 
and  those  in  which  the  time  is  recorded  directly.  As  the 
muzzle  velocity  attained  by  projectiles  from  modern  high 
velocity  rifled  arms  is  usually  from  2000  to  2500  ft.  per 
second,  the  time  recorder  must  be  capable  of  recording 
small  intervals  of  time.  The  passage  of  the  projectile  over 
the  space  in  which  its  velocity  is  being  determined  is  indicated 
by  placing  thin,  brittle  copper  wires  in  its  path,  the  projectile 
severing  these  wires  and  thus  breaking  an  electric  circuit 
so  arranged  that  this  interruption  is  recorded. 

Le  Boulenges  Chronograph  is  shown  diagrammatically 
in  Fig.  32.  The  fracture  by  the  projectile  of  the  first  wire 
breaks  the  circuit  of  the  electro-magnet  A,  and  allows  the 
weight  B  to  fall.  This  weight  is  in  the  form  of  a  tube 
sliding  freely  over  a  vertical  rod,  so  that  it  can  fall  freely 
in  an  upright  condition,  but  cannot  topple  over.  To  avoid 


EXPLOSIVE  PROPERTIES 


203 


all  chance  of  friction  between  the  tube  and  the  rod  the  latter 
is  sometimes  omitted,  but  in  this  case  it  is  difficult  to  be  cer- 
tain of  the  weight  falling  true.  The  fracture  by  the  projectile 
of  the  second  wire  breaks  the  circuit  of  the  magnet  C,  and 
allows  the  weight  D  to  fall  on  to  the  button  B.  This  latter 
is  connected  with  a  trigger  and  spring  arrangement,  not 
shown  in  the  diagram,  so  that  when 
struck  it  releases  the  knife  point  F, 
which,  being  actuated  by  the  spring, 
strikes  the  falling  weight  B,  and 
leaves  a  mark  on  its  soft  metal 
covering.  By  holding  C  with  this 
mark  in  contact  with  F  and  then 
measuring  the  distance  between  the 
top  of  the  weight  and  the  bottom 
of  the  electro-magnet  A,  the  distance 
which  the  weight  has  fallen  can  be 
found,  and  from  this  the  time  cal- 
culated. There  are,  however,  several 
sources  of  error  in  the  figures  thus 
obtained,  and  these  must  be  cor- 
rected. In  the  first  place,  there  is 
the  lag  in  the  demagnetization 
(hysteresis)  of  the  two  magnets, 
which  may  or  may  not  be  the 
same;  and  in  the  second  place, 
there  is  the  time  taken  by  the  weight 
D  in  reaching  K  and  the  time  occupied  by  F  in  springing 
forward.  These  errors  are  best  allowed  for  by  determining 
a  zero  value,  this  being  done  by  breaking  the  two  circuits 
simultaneously.  When  this  is  done  the  distance  fallen  by 
B  represents  the  magnitude  of  the  lag  due  to  electrical 
and  mechanical  delays,  and  is  to  be  allowed  for  when 
calculating  velocity. 

This  instrument  is  simple  to  use,  and  gives  very  fair 
results  over  short  distances,  but  when  measuring  a  com- 
paratively large  interval  of  time  the  experimental  error 
becomes  big.  This  is  due  to  the  fact  that  when  a  body 


TE 


FIG.  32. — Le  Boulenge 
Chronograph. 


204  EXPLOSIVES 

falls  under  constant  acceleration,  in  this  case  the  accelera- 
tion due  to  gravity,  the  space  traversed  varies  as  the  square 
of  the  time  — 

s  = 


or  taking  the  value  of  /  as  32  in  foot-seconds  units  — 


So  long  as  S  is  small,  slight  experimental  error  does  not 
affect  t  to  any  great  extent,  but  when  S  becomes  compara- 
tively large  experimental  error  affects  t  severely. 

To  overcome  this  difficulty  Le  Boulange  devised  an 
instrument  which  he  named  the  Klepsydra,  and  which  was 
based  on  the  sand-glass  principle.  It  consisted  of  a  T- 
shaped  vessel  rilled  with  mercury,  the  foot  of  the  T  being 
provided  with  a  needle  valve.  This  was  actuated  elec- 
trically, the  breaking  of  the  first  wire  opening  the  valve, 
and  the  breaking  of  the  second  wire  closing  it.  By  weighing 
the  mercury  which  ran  out  in  the  interval  the  time  during 
which  the  valve  was  open  could  be  deduced.  Zero  value 
was  obtained  by  breaking  both  ciicuits  simultaneously. 

The  Bashforth  Chronograph  is  based  on  a  different 
principle,  the  time  being  measured  by  the  beat  of  a  pendu- 
lum. It  consists  of  a  revolving  drum  covered  with  smoked 
paper  and  geared  to  a  board  in  such  a  way  that  as  the  drum 
revolves  the  board  descends  in  a  vertical  direction.  The 
board  carries  two  styles  which  are  held  away  from  the 
surface  of  the  smoked  paper  by  means  of  electro-magnets. 
The  circuits  of  these  magnets  are  broken  in  succession  by 
the  projectile,  thus  allowing  the  styles  to  spring  forward 
and  mark  the  smoked  paper  on  the  drum.  By  means  of  a 
similar  arrangement  the  pendulum  makes  time  marks  on 
the  paper  so  that  the  time  that  has  elapsed  between  the 
breaking  of  the  two  circuits  is  readily  read  off. 

As  inLe  Boulange's  instrument,  electrical  and  mechanical 
lag  is  corrected  for  by  breaking  the  circuits  simultaneously. 

The  Schultze-Marcel-Dieprez  Chronograph  is  somewhat 
similar  in  construction,  the  breaking  of  the  circuits  of 


EXPLOSIVE  PROPERTIES  205 

electro-magnets  causing  points  to  impinge  on  smoked  paper 
attached  to  a  revolving  drum.  In  this  instrument,  however, 
time  is  marked  simultaneously  as  a  sinuous  curve  by  means 
of  a  tuning  fork  of  definite  note,  a  style  being  attached  to 
one  prong  and  this  style  being  in  contact  with  the  revolving 
drum.  The  tuning-fork  is  one  of  the  most  convenient 
methods  of  recording  moderately  short  intervals  of  time, 
and  is  widely  used  in  all  branches  of  physics.  As  a  matter 
of  convenience  the  fork  may  be  electrically  controlled. 

The  Mahieu  Chronograph  is  very  similar  to  the  above, 
but  the  drum  in  addition  to  a  rotatory  movement  has  also 
a  longitudinal  movement.  The  pens  are  in  permanent 
contact  with  the  surface  of  the  paper,  but  are  attached  to 
springs  so  that  they  spring  to  one  side  when  the  circuits 
of  the  electro- magnets  are  broken,  thus  causing  a  sudden 
momentary  change  in  direction  in  the  line  being  traced. 
The  gearing  controlling  the  relative  longitudinal  and  rotatory 
movement  of  the  drum  is  capable  of  alteration  so  as  to 
render  the  instrument  suitable  for  measuring  high  and  low 
velocities  and  of  dealing  with  both  short  and  long  flights. 

Of  course,  either  the  Bashforth,  the  Schultze  or  the 
Mahieu  instrument  can  be  used  for  studying  the  velocity 
of  a  projectile  at  different  points  of  its  flight,  it  being  only 
necessary  to  add  more  pens,  but  the  Mahieu  instrument  is 
best  adapted  for  work  of  this  nature. 

LITERATURE 

A  good  general  description  of  the  tests  applied  to  Explosives  \\ill  be 
found  in  U.S.  Bureau  of  Mines,  Technical  Paper  No.  186. 

POWER 

Conditions  for  the  Trauzl  lead  block  test  are  given  in  the  "  Report  of 
the  Fifth  International  Congress  of  Applied  Chemistry,"  1903,  vol.  ii.  p.  286. 

See  also  C.r.,  1907,  1032  ;  S.S.,  1907,  p.  313  ;  Z.  ang.,  1911,  2234. 

The  American  ballistic  pendulum  is  described  in  detail  in  Bulletin 
of  the  U.S.  Bureau  of  Mines,  No.  15,  p.  79,  other  tests  being  discussed 
also.  The  British  pendulum  at  Rotherham  is  described  in  A  .R.,  1912, 
p.  83. 

See  also  S.5.,  1913,  p.  265.  "  VIII.  Congress  of  Applied  Chemistry," 
vol.  25,  p.  209. 

BRISANCE 

Kast,  "  Spreng-  u.  Zund-stoffe,"  1031.  S.S.,  1906,  p.  151  ;  1913.  P-  89- 


206  EXPLOSIVES 

VELOCITY  OF  DETONATION 

C.  E.  Bichel,  "  Testing  Explosives,"  English  translation  by  A.  Larnsen, 
London,  1905. 

Kast,  "  Spreng-  u.  Zund-stoffe,"  1025. 

"  V.  Congress  of  Applied  Chemistry,"  vol.  ii.  p.  327. 

"  VIII.  Congress  of  Applied  Chemistry,"  vol.  iii.  b,  p.  28. 

Bulletin  of  the  U.S.  Bureau  of  Mines,  No.  15,  p.  92. 

C.Y.,  143,  641.  P.5.,  xvi.  27;  xvii.  154.  S.S.,  1908,  p.  403;  1913 
pp.  65,  88,  90,  133,  155,  172. 

PRESSURE 

A.  Nobel,  "  Artillery  and  Explosives," 
C.  E.  Bichel,  "  Testing  Explosives." 

Phil.  Trans.,  1905,  p.  357.    5.5.,  1908,  p.  366. 

HEAT 

C.  E.  Bichel,  "  Testing  Explosives." 
5.5.,  1907,  pp.  281,  306  ;   1908,  p.  406. 
Bulletin  of  U.S.  Bureau  of  Mines,  No.  15,  p.  in. 

TEMPERATURE 
C.v.,  1881,  1014. 
Z.  el.  ch.,  1909,  536  ;   1910,  897. 
S.S.,  1907,  p.  306  ;    1909,  pp.  281,  305,  388  ;    1910,  pp.  205,  248,  266, 

291,  31°.  376,  399,  452,  474- 

Bulletin  of  U.S.  Bureau  of  Mines,  No.  15. 

CHRONOGRAPHY  AND  BALLISTICS 

F.  Bashforth,  "  Experiments  made  with  the  Bashforth  Chronograph," 
Cambridge,  1890-1900. 

B.  Glatzel,    "  Elektrische    Methoden    der    Momentanphotographie," 
Brunswick,  1915. 

J.  M.  Ingalls,  "  Interior  Ballistics,"  New  York,  1912. 
P.  Charbonniere,  "  Balistique  Interieure,"  Paris,  1908. 

C.  Cranz,  "  Lehrbuch  der  Ballistik,"  3  vols.     Berlin,  1910-1913. 

A.  C.  Crehore  and  G.  O.  Squier,  "  Polarizing  Photo-Chronograph," 
New  York,  1897. 

T.  Kozak,  "  Einfuhrung  in  die  aussere  Ballistik,"  Vienna,  1911. 

The  photography  of  the  air  disturbance  caused  by  a  projectile  is 
described  in  5.5.,  1911,  pp.  261,  330. 


SECTION  IX.— SENSITIVENESS  AND 
STABILITY 

AN  explosive  must  fulfil  certain  conditions  as  regards 
sensitiveness  and  stability  if  it  is  to  be  suitable  for  com- 
mercial use.  Unless  intended  for  use  as  an  initiator  in 
percussion  caps  or  detonators  it  should  not  be  unduly 
sensitive  to  mechanical  shock,  as  if  it  is  it  will  be  unsafe 
to  handle  and  transport.  At  the  same  time  it  must  be 
moderately  sensitive  to  detonation  and  should  be  exploded 
fairly  easily  by  influence,  i.e.  by  the  explosion  of  another 
cartridge  of  the  same  explosive  lying  near  it  but  not  actually 
in  contact  with  it.  A  moderate  degree  of  sensitiveness  to 
explosion  by  influence  is  very  desirable,  as  in  blasting 
operations  the  bore-holes  are  usually  charged  with  several 
cartridges  which  may  be  separated  from  one  another  by 
an  air  space  due  to  defective  ramming  or  by  a  layer  of  dust 
that  has  fallen  into  the  hole  during  charging.  Only  one 
-cartridge  carries  a  detonator,  and  hence  if  the  explosive 
is  not  readily  exploded  by  influence  some  of  the  cartridges 
may  fail  to  detonate  and  may  cause  an  accident  by  being 
struck  with  a  pick  or  shovel  later  on. 

Stability  is  also  highly  desirable  in  an  explosive  intended 
for  practical  use,  as  should  chemical  decomposition  take 
place  during  storage  either  the  explosive  may  fail  to  detonate 
owing  to  loss  of  explosive  properties,  e.g.  mercury  fulminate, 
or  it  may  become  excessively  sensitive  or  even  explode 
spontaneously,  e.g.  chlorate-sulphur  mixtures.  All  organic 
nitric  esters  have  a  tendency  to  decompose  spontaneously  at 
the  ordinary  temperature  with  the  production  of  nitric  acid. 
In  most  cases  the  reaction  is  an  extremely  slow  one,  but  the 
velocity  is  greatly  increased  by  the  catalytic  effect  of  acids. 


208  EXPLOSIVES 

Since  acid  is  actually  produced  by  the  decomposition  the 
reaction  is  auto-catalytic,  and  hence  it  is  of  the  utmost 
importance  to  test  all  explosives  to  determine  the  relative 
rate  of  production  of  acid.  The  Abel  Heat  Test  is  designed 
for  this  purpose,  and  in  spite  of  its  numerous  imperfections 
gives  a  fair  idea  of  stability.  Chlorate-sulphur  mixtures 
become  dangerous  from  a  similar  cause,  as  atmospheric 
oxygen  converts  traces  of  the  sulphur  into  sulphuric  acid, 
this  in  turn  liberating  the  highly  dangerous  chloric  acid. 

In  addition  to  chemical  stability,  physical  stability  is 
also  of  importance.     Thus  most  explosives  containing  nitro- 
glycerine are  liable  to  "  sweat  "  or  "  exude  "  this  substance, 
and  as  nitroglycerine  is  very  sensitive  to  shock,  the  sensitive- 
ness of  the  explosive  is  greatly  increased  although  no  chemical 
decomposition  has  taken  place.     Blasting  gelatine  is  par- 
ticularly  liable   to   exude,    exudation   from  Gelignite   and 
Gelatine    Dynamite    being    hindered    by    the    absorptive 
properties  of  the  wood  meal  used  for  doping  these  explosives. 
Deliquescence  is  another  example  of  what  may  be  termed 
physical  stability.     Explosives  containing  hygroscopic  sub- 
stances such  as  nitrate  of  ammonia  take  up  moisture  rapidly 
and  may  become  quite  unfit  for  use  in  a  short  time.     The 
behaviour  of  an  explosive  when  subjected  to  heat  is  also 
important,  as  is  its  behaviour  when  ignited,  it  being  pre- 
ferable from  a  safety  point  of   view  that  under  these  cir- 
cumstances it  should  burn  away  quietly  without  exploding. 
Finally,  with  powdered  explosive  mixtures  degree  of  incor- 
poration must  be  examined,  as  if  not  properly  incorporated 
the  constituents  may  separate  when  submitted  to  vibration, 
e.g.   during   transport,   the  explosive  subsequently  giving 
irregular  results. 

MECHANICAL  SHOCK 

Mechanical  shock  may  be  of  two  types,  viz.  shock  due 
to  friction  or  shock  due  to  a  direct  blow.  Comparative  tests 
to  determine  the  relative  sensitiveness  to  friction  of  two 
explosives  are  difficult  to  carry  out  owing  to  the  impossi- 
bility of  fixing  a  standard  of  friction,  but  a  rough  idea  can 


SENSITIVENESS  AND  STABILITY 


209 


be  obtained  by  various  means  such  as  grinding  the  samples 
in  a  mortar  under  as  similar  conditions  as  possible,  striking 
them  a  glancing  blow  either  by  hand,  or,  better,  by  means 
of  a  pendulum  arrangement. 

A  direct  blow  is  much  more  easily  imitated,  and  the 
falling  weight  test  is  invariably  made  use  of.     The  apparatus 

for  this  consists  of  an  anvil  surrounded       ^ ^ 

by  a  cylinder  in  which  a  piston  works 
freely  in  a  vertical  direction,  but  is 
incapable  of  lateral  movement.  The 
explosive  is  spread  on  the  anvil  and  the 
piston  inserted  into  the  cylinder  so  that 
its  lower  end  rests  on  the  explosive. 
The  upper  end  of  the  piston  is  then 
struck  a  blow  by  a  definite  weight  falling 
from  a  definite  height,  the  height  being 
gradually  increased  until  explosion  takes 
place.  The  falling  weight  slides  freely 
over  vertical  guide  rods  so  as  to  assure 
its  falling  true  and  striking  a  direct  and 
not  a  glancing  blow.  The  apparatus  is 
shown  in  Fig.  33. 

Theoretically  the  force  of  the  blow  is 
given  by  the  mass  of  the  falling  weight 
multiplied  by  the  velocity  with  which  it 

strikes,  or — 

FIG.  33. — Falling 

F  =  M  X  V  2gS      Or  F  =  8MV  S  Weight  Test. 

where  M  is  the  mass  of  the  falling  weight,  S  the  height 
through  which  it  has  fallen,  and  g  the  acceleration  due  to 
gravity.  In  other  words,  the  force  of  the  blow  should  be 
proportional  to  the  product  of  the  weight  into  the  square 
root  of  the  height.  In  practice  this  is  not  the  case,  but  the 
test  is  not  of  sufficient  accuracy  to  be  susceptible  to  mathe- 
matical treatment.  For  one  thing,  the  results  depend  on 
the  thickness  of  the  layer  of  the  explosive,  its  physical 
nature  (density,  size  of  grain,  etc.),  nature  of  the  surfaces 
with  which  it  is  in  contact,  temperature,  etc. ;  and  hence, 
T.  14 


210  EXPLOSIVES 

in  order  to  obtain  comparable  results,  the  measurements 
must  be  made  under  strictly  standard  conditions.  These 
have  been  laid  down  by  an  International  Committee  as 
follows : — 

The  anvil  and  the  piston  are  made  of  hardened  steel, 
the  former  resting  on  a  firm  foundation,  and  the  area  of 
each  is  127  mm.2  (1*27  cm.  in  diameter).  The  weight 
of  explosive  used  is  '05-' i,  the  amount  being  chosen  so  as 
to  give  a  layer  of  standard  thickness  when  spread  uniformly 
on  the  anvil.  The  sample  is  dried  over  calcium  chloride 
before  use,  and  a  fresh  quantity  taken  for  each  experiment. 
The  standard  temperature  is  i8°-20°  C.,  and  the  weight  used 
weighs  two  kilograms. 

Although  these  are  the  "  Official "  conditions  they  cannot 
as  yet  be  said  to  be  generally  adopted,  and  most  data  avail- 
able have  been  obtained  under  somewhat  different  conditions. 
The  following  results  give  a  fair  idea  of  the  figures  obtained, 
and  were  given  by  Will  at  the  VI.  Congress  of  Applied 
Chemistry.  He  used  *i  gram  of  explosive  which  had  been 
dried  at  40°  C.,  and  which  was  confined  between  steel  surfaces 
and  struck  by  a  falling  weight  of  2  kilos. : — 

Mercury  Fulminate         . .         . .         . .  2    cm. 

Nitroglycerine  (dry)        . .          . .          . .  4 

I/ead  picrate         . .          . .          . .          . .  5       ,, 

Dinitroglycerine              . .          . .          . .  7 

Dynamite  No.  i              . .         . .  7      ,, 

(frozen) 25 

Blasting  Gelatine            . .         . .         . .  12 

(frozen)         ..          ..  12-15  ,, 

Gelatine  Dynamite         . .         . .         . .  17 

Gunpowder  (sporting)     . .         . .  70      „ 

(blasting) 85      „ 

Cheddite,  Type  60           32 

Type  41           36       ,, 

Tetryl        40-65  ,, 

Hexa-nitrodiphenylamine          . .          . .  40 

T.N.T 57-i8o  „ 

Dinitrobenzene     . .          . .          . .  120     ,, 

Tri-nitronaphthalene 175    ,, 


SENSITIVENESS  AND  STABILITY         211 


Ammonium  picrate 
Picric  Acid 

Guncotton  (15  %  H2O)  . . 
Collodion  (15  %  H2O)  . . 
Nitrocellulose  propellants 

Astralite 

Donarite 

Guncotton  (20  %  H2O)  . . 


Collodion  (20  % 


H2O) 


. .     80    cm. 

•  •  35-95  » 
..85      „ 
. .     100     ,, 

•  •  30-54  .. 
..     no    „ 
..     no    „ 

over  185     „ 
over  185     „ 


The  following  figures  give  a  rough  idea  of  the  result  of 
using  different  weights,  in  all  cases  'i  gram  of  explosive 
being  used,  and  this  being  wrapped  in  tinfoil.  The  falls 
are  given  in  centimetres — 


Explosive. 

Composition. 

•i  Kg. 

•5  Kg. 

I  Kg. 

2    Kg. 

5  Kg. 

Guncotton 

Dry 

30-40 

5-10 

5-10 

5-10 

_ 

>i 

15  %  H20 

15-20 

10-15 

10-15 

5-10 

Picric  Acid 

Crystalline 

—  . 

— 

190-200 

IOO-IIO 

50-60 

M 

Compressed 

— 

— 

—  . 

140-150 

80-90 

T.N.T.  .  . 

Crystalline 

—  . 

— 

180-190 

90—100 

50-60 

»»       •  • 

Compressed 

- 

— 

— 

150-160 

80-90 

N.G.        30           ) 

Carbonite  No.  2 

NaN03  24-5 
Flour      40-5        j 

60-70 

IO-2O 

IO-2O 

IO-2O 

— 

K2Cr2O7  5-0        J 

N.G.          3'8 

C.C.                   '2 

Donarite 

AmNO3  80-0 

— 



120-130 

60-70 

15-20 

T.N.T.     12-0 

Flour        4*0 

The  U.S.  Bureau  of  Mines  make  use  of  a  much  larger 
machine  in  which  greater  quantities  of  explosive  (20  grams) 
can  be  used.  The  falling  weight  weighs  200  kilos.,  and  it  is 
claimed  that  the  figures  obtained  are  of  greater  value,  as 
actual  practical  conditions  of  use  are  more  nearly  imitated. 
The  results  obtained  with  this  machine  are  quite  different 
from  those  obtained  by  the  smaller  machines. 

DETONATION 

Sensitiveness  to  detonation  depends  largely  on  the 
physical  state  of  the  explosive  undergoing  test,  and  almost 


212  EXPLOSIVES 

invariably  decreases  with  increasing  density,  at  high 
densities  most  explosives  becoming  so  insensitive  that  they 
either  cannot  be  detonated  at  all  or,  if  detonated,  the  detona- 
tion is  incomplete.  At  low  temperatures  sensitiveness  is 
also  diminished,  while  at  elevated  temperatures,  as  would 
be  expected,  the  reverse  is  the  case. 

Ease  of  detonation  is  very  simply  determined  by  firing 
cartridges  of  the  explosive  with  detonators  of  different 
power,  and  thus  finding  the  weakest  that  will  cause  complete 
detonation  under  the  conditions  of  the  experiment.  In  the 
case  of  insensitive  explosives  that  require  a  primer  of  some 
more  sensitive  explosive  in  order  to  detonate  them  completely 
the  minimum  weight  of  the  primer  is  determined  in  the  same 
way. 

INFLUENCE 

The  capacity  of  one  cartridge  of  an  explosive  to  detonate 
another  cartridge  separated  from  it  by  an  air  space  depends 
on  the  sensitiveness  of  the  explosive  and  on  the  velocity  of 
detonation,  and  hence  also  on  the  physical  state  of  the 
explosive.  It  also  depends  on  the  nature  of  the  surface  on 
which  the  cartridges  are  resting,  being  at  a  minimum  when 
they  are  suspended  so  that  the  wave  of  detonation  can  only 
be  transmitted  through  the  air,  and  at  a  maximum  when  the 
cartridges  are  resting  on  some  hard,  solid  substance  such  as 
iron,  in  which  case  the  wave  of  detonation  is  no  doubt 
largely  transmitted  through  the  solid  body.  The  distance 
through  which  detonation  is  transmitted  is  determined  by 
the  method  of  trial  and  failure,  cartridges  being  exploded  at 
increasing  distances  until  the  detonation  is  no  longer  trans- 
mitted from  one  to  another.  The  figures  thus  obtained 
depend  very  much  on  the  explosive,  and  vary  from  a  small 
fraction  of  an  inch  to  several  feet.  They  also  depend  largely 
on  the  quantity  of  explosive  involved,  the  explosion  of  large 
amounts,  as  for  example  during  an  accident,  being  capable 
of  exploding  other  explosives  at  a  considerable  distance. 

With  reference  to  this  experiments  have  been  carried 
out  to  determine  the  velocity  with  which  the  wave  of 
detonation  is  transmitted  through  air,  This  was  done  with 


SENSITIVENESS   AND  STABILITY         213 

detonating  fuze  in  much  the  same  way  that  velocity  of  detona- 
tion (page  187)  is  determined,  two  cartridges  being  separated 
from,  but  hanging  end  on  to  one  another,  and  detonators 
inserted  into  the  inner  ends  and  connected  by  detonating 
fuze.  One  of  the  cartridges  was  then  fired  by  an  independent 
detonator,  and  the  velocity  of  the  wave  of  detonation  through 
the  air  space  determined  by  the  behaviour  of  the  fuze.  It 
was  found  that  the  wave  of  detonation  starts  through  the 
air  with  about  the  same  velocity  as  it  has  in  the  cartridge, 
but  that  there  is  a  retardation  of  about  50  metres  per  second 
for  every  centimetre  of  air  traversed. 

HEAT  AND  IGNITION 

The  temperature  at  which  an  explosive  ignites  or  explodes 
depends  on  how  rapidly  the  temperature  is  raised,  and  is  not 
a  definite  value  like  the  melting-point  of  a  pure  chemical 
compound.  It  is  rather  analogous  to  the  melting-point  of 
a  chemical  compound  in  which  decomposition  sets  in  before 
its  melting-point  is  reached,  so  that  if  the  heating  takes 
place  slowly  an  indefinite  value  is  obtained,  whereas  if 
the  heating  is  rapid  a  fairly  definite  point  can  be  deter- 
mined at  which  the  compound  melts  before  decomposition 
has  gone  far  enough  to  have  much  effect.  Hence,  in  deter- 
mining the  ignition  point  of  an  explosive  a  preliminary 
experiment  should  first  be  carried  out  in  which  the  heating 
is  slow  in  order  to  determine  an  approximate  value,  and 
then  a  more  accurate  measurement  made  in  which  the 
apparatus  is  pre-heated  to  this  point  before  the  explosive 
is  introduced.  By  this  means  it  has  been  found  that  nitro- 
glycerine explodes  at  about  170°  C.  and  nitrocellulose  at 
io°-20°  higher. 

From  the  point  of  view  of  safety  it  is  desirable  that 
an  explosive  should  burn  away  quietly  without  ex- 
ploding if  accidentally  ignited,  but  the  behaviour  of  an 
explosive  under  these  circumstances  depends  largely  on 
how  the  ignition  is  started,  the  degree  of  confinement  of  the 
explosive,  and  on  the  quantity.  Hence  laboratory  results 
are  of  comparatively  little  value,  although  more  or  less 


214  EXPLOSIVES 

useful  indications  can  be  obtained  by  igniting  small  quantities 
in  various  ways,  such  as  by  means  of  a  match  or  a  piece  of 
safety  fuze,  or  by  throwing  some  of  the  explosive  into  a  hot 
dish.  As  a  rule,  when  in  small  quantity,  nitroglycerine 
explosives  burn  away  fiercely,  but  do  not  explode,  but  with 
larger  quantities  explosion  generally  takes  place.  Ex- 
plosives containing  chiefly  ammonium  nitrate  and  small 
quantities  of  nitroaromatic  compounds,  on  the  other  hand, 
are  almost  incombustible,  but  large  quantities  submitted 
to  a  high  temperature  may  explode. 

INCORPORATION 

Black  powder  and  other  explosives  containing  only  solid 
constituents,  such  as  ammonium  nitrate  explosives,  if  not 
sufficiently  incorporated,  may  settle  out  when  submitted  to 
vibration  during  transport,  and  thereafter  either  do  not 
explode  at  all  or  give  very  irregular  results.  To  ascertain 
if  the  incorporation  is  satisfactory  a  sample  of  the  explosive 
is  submitted  to  vibration  for  a  number  of  hours  in  a  type  of 
shaking  machine.  This  is  best  constructed  in  such  a  way 
that  the  vessel  containing  the  explosive  is  raised  by  a  cam 
or  sprocket  wheel  and  lever  and  then  allowed  to  drop 
back  on  to  a  metal  stop.  After  a  period  of  vibration  the 
top  layer  and  the  bottom  layer  of  the  explosive  are  collected 
separately  and  analyzed. 

DEUQUESCENCE 

The  capacity  of  an  explosive  to  absorb  moisture  from  the 
air  is  an  important  point,  especially  with  those  explosives 
which  contain  highly  hygroscopic  salts  such  as  nitrate  of 
ammonia  or  soda,  as  the  absorption  may  reach  such  a  point 
that  the  explosive  can  no  longer  be  detonated,  or  in  the  case 
of  nitroglycerine  explosives  the  water  taken  up  may  displace 
the  nitroglycerine  and  thus  give  rise  to  danger.  The  deli- 
quescence of  an  explosive  depends  chiefly  on  its  constituents, 
but  is  also  influenced  by  the  method  of  incorporation,  non- 
deliquescent  ingredients  such  as  nitroaromatic  compounds 
acting  to  some  extent  as  waterproofing  when  the  incorpora- 
tion has  been  carried  out  hot.  Deliquescence  being  a  surface 


SENSITIVENESS  AND  STABILITY         215 

action  also  naturally  depends  on  the  size  of  the  grain  and 
on  the  porosity.  In  examining  an  explosive  for  deliquescence 
the  most  satisfactory  method  is  to  compare  its  behaviour 
in  this  respect  with  another  explosive  under  similar  circum- 
stances. This  is  very  simply  done  by  spreading  known 
weights  on  watch  glasses  and  then  exposing  them  to  the 
atmosphere  for  the  same  number  of  hours  and  noting  the 
increase  in  weight.  As  the  humidity  of  the  atmosphere 
varies  from  day  to  day  it  is  better  to  expose  the  samples 
in  a  closed  cupboard  maintained  at  a  constant  temperature, 
the  humidity  of  the  air  being  maintained  by  flat  dishes 
containing  water  or  saturated  solutions  of  salts. 

EXUDATION 

The  British  Home  Office  regulations  for  testing  for 
exudation  lay  down  that  a  section  of  the  cartridge  approxi- 
mately equal  in  length  to  its  diameter  shall  be  cut  so  that 
the  ends  are  flat  and  the  edges  sharp.  This  is  then  pinned 
on  to  a  flat  surface  with  its  axis  vertical  by  a  pin  passing 
through  the  centre  and  exposed  to  a  temperature  of  85°  to 
90°  Fahr.  (29-4°  to  32-2°  C.)  without  any  wrapper  for  144  con- 
secutive hours,  at  the  end  of  which  time  the  upper  cut 
surface  must  still  be  flat  and  the  edges  sharp,  and  the  diminu- 
tion of  height  must  not  exceed  25  per  cent.  American 
Straight  Dynamites  are  very  apt  to  exude  nitroglycerine 
through  absorption  of  water,  and  in  the  United  States  three 
tests  are  in  use.  In  one  the  explosive  is  pressed  for  i  minute 
between  pads  of  cotton  wool  at  80  Ibs.  per  square  inch  and 
must  not  show  a  loss  of  more  than  3  per  cent.  In  the 
second  test  it  is  submitted  to  centrifugal  force  when  enclosed 
between  cotton  wool,  and  again  in  this  case  the  loss  must 
not  exceed  3  per  cent.  Finally  it  is  placed  in  a  vertical 
position  and  heated  for  6  days  at  40°  C. 

INTERNATIONAL  COMMITTEE 

In  1912  the  International  Committee  on  Tests  for 
Explosives  recommended  that  the  following  tests  should 


216  EXPLOSIVES 

be  applied  to  explosives  in  order  to  ascertain  their  safety 
for  transport  :— 

I.  Preliminary  Test 

Two  samples  each  of  ten  grams  of  the  non-desiccated 
explosive  are  placed  in  glass  capsules  fitted  with  a  cover 
and  having  a  diameter  of  35  mm.  and  a  height  of  50  mm. 
The  samples  are  heated  to  75°  C.  for  4  hours,  and  at  the  end  of 
that  time  no  decomposition  or  change  in  appearance  must 
have  taken  place,  and  no  smell  must  be  noticeable. 

II.  Mechanical  Shock 

The  explosive  is  dried  and  powdered,  and  '05-*  10  gram 
is  spread  on  a  steel  anvil  in  a  layer  1*27  cm.  in  diameter  and 
tested  by  the  falling  weight.  The  explosive  must  not  be 
more  sensitive  than  an  equal  weight  of  pure,  dry  powdered 
picric  acid  when  tested  under  exactly  similar  conditions. 

III.  Friction 

The  explosive  is  ground  in  an  unglazed  porcelain  mortar 
at  a  temperature  of  25°-30°  C.,  and  its  behaviour  compared 
with  that  of  picric  acid  under  similar  treatment. 

IV.  Fire 

(a)  Three  grams  of  the  explosive  are  tapped  down  into 
a  glass  test  tube  and  its  behaviour   towards  slow-burning 
safety  fuse  tested.    If  it  ignites  it  must  be  classified  as 
deflagrating  and  easily  inflammable. 

(b)  The  explosive  is  thrown  into  a  hemispherical  iron 
dish,  12  cm.  in  diameter,  at  a  red  heat.     At  first  only  -5 
gram  of  the  explosive  is  used,  but  if  this  does  not  explode 
or  ignite  the  amount  is  gradually  increased  to  5  grams. 

(c)  One  hundred  grams  are  placed  on  a  sheet  of  asbestos 
board  and  then  touched  with  an  iron  rod  15  mm.  in  diameter 
heated  to  a  cherry-red  heat  (about  900°  C.).     The  explosive 
should   only   burn  slowly,  and  must  not  detonate.    The 
ignition  should  die  out  when  the  hot  rod  is  removed. 

The  Committee  printed  their  recommendations  in  both 
French  and  English,  but  the  English  version  is  so 


SENSITIVENESS  AND  STABILITY         217 

ungrammatical  that  the  foregoing  description  is  abstracted 
from  the  French. 

THE  HEAT  TEST 

The  test  known  as  the  Heat  Test  was  originally  intro- 
duced by  Abel  for  testing  the  stability  of  guncotton,  and 
depends  upon  the  time  required  to  produce  a  given  tint  in 
starch-iodide  paper  when  the  explosive  is  heated  under 
standard  conditions.  The  exact  conditions  under  which 
the  test  is  carried  out  have  been  modified  from  time  to  time, 
but  in  1909  the  British  Government  appointed  a  depart- 
mental committee  to  investigate  the  whole  matter  and  to 
specify  standard  conditions  for  the  test  as  applied  to  ex- 
plosives of  various  classes,  and  this  committee  presented  its 
First  Report  in  1914.  In  Great  Britain  the  Heat  Test  is  the 
standard  test  of  stability  applied  to  all  explosives,  and  unless 
an  explosive  satisfies  this  test  it  may  neither  be  sold  nor 
transported.  Owing  to  the  great  importance  lent  to  the 
test  by  these  regulations  the  conditions  under  which  it  is 
carried  out  will  be  described  in  some  detail. 

In  carrying  out  work  with  the  heat  test  it  must  be  borne 
in  mind  that  it  is  exceedingly  sensitive,  and  hence  the  most 
scrupulous  cleanliness  is  absolutely  essential.  A  special 
room  must  be  devoted  to  it,  the  floor  and  walls  of  which 
are  washed  at  frequent  intervals,  no  reagents  other  than 
those  required  for  the  test  should  be  allowed  into  the  room, 
and  the  room  should  be  situated  as  far  as  possible  from  the 
acid  department.  The  room  should  be  entered  by  as  few 
people  as  possible,  and  the  operator  must  wash  his  hands 
and  rinse  them  with  distilled  water  at  frequent  intervals. 
Direct  sunlight  should  also  be  excluded  from  the  room. 

Most  factories,  especially  those  holding  Government 
contracts,  purchase  their  test  papers  from  the  Royal  Gun- 
powder Factory  at  Waltham  Abbey,  but  the  following  official 
regulations  have  been  laid  down  for  their  preparation  : — 

The  purest  potassium  iodide  obtainable  commercially 
is  to  be  purified  immediately  before  use  by  triple  recrystalli- 
zation  from  pure  ethyl  alcohol  diluted  with  one-twentieth 


218  EXPLOSIVES 

of  its  own  volume  of  distilled  water.  The  crystals  are  to 
be  kept  as  small  as  possible  and  are  to  be  dried  in  the  dark 
on  clean  filter  paper  resting  on  a  glass  plate.  When  dry 
they  are  to  be  laid  in  a  thin  layer  at  the  bottom  of  a  platinum 
crucible  and  heated  to  dull  redness  for  one  minute,  a  .spirit 
lamp  burning  pure  alcohol  being  used. 

The  starch  is  to  be  best  maize  starch  in  the  form  of 
cornflour.  Immediately  before  use  it  is  washed  six  times 
with  freshly  distilled  water,  and  then  dried  in  a  warm  room 
in  the  dark  on  an  unglazed  porcelain  plate. 

The  solution  is  prepared  by  suspending  3  grams  of 
starch  in  30  c.c.  of  distilled  water  and  then  pouring  the 
suspension  into  220  c.c.  of  freshly  distilled  boiling  water 
contained  in  a  Jena  glass  flask.  The  whole  is  then  kept 
gently  boiling,  with  occasional  shaking,  for  5  minutes,  a 
spirit  lamp  burning  pure  alcohol  being  used.  The  solution 
thus  obtained  is  poured  into  a  solution  of  i  gram  of  potassium 
iodide  in  250  c.c.  of  distilled  water,  and  the  whole  well  mixed 
and  allowed  to  stand  overnight  in  a  dark  room.  The  follow- 
ing day  the  clear  supernatant  liquid  is  syphoned  off  and 
immediately  used  for  dipping.  This  is  done  by  pouring  the 
solution  into  a  porcelain  tray  reserved  for  the  purpose,  and 
then  passing  sheets  of  filter  paper  through  it  singly  so  that 
all  except  3  cm.  at  the  end  of  the  strip  passes  beneath  the 
surface  of  the  liquid.  The  paper  is  then  hung  up  by  the  dry 
part  and  a  clean  glass  rod  passed  down  each  side  to  remove 
the  excess  of  solution,  after  which  it  is  allowed  to  dry  in  a 
warm  dark  room.  When  dry  the  undipped  part  is  cut  off, 
and  also  strips  -5  cm.  wide  round  the  edges,  these  portions 
being  rejected.  The  remainder  is  then  cut  into  rectangular 
slips  2  cm.  long  and  i  cm.  wide  and  preserved  for  use 
in  brown  glass  bottles.  While  cutting  up  the  paper  the 
operator  is  to  wear  clean  cotton  gloves,  and  the  preparation 
of  the  paper  is  to  be  carried  out  in  a  special  room  reserved 
for  the  purpose  and  kept  as  dark  as  is  compatible  with  the 
carrying  out  of  the  work.  The  Memorandum  issued  by  the 
committee  describes  a  method  of  testing  the  sensitiveness 
of  the  papers  thus  prepared. 


SENSITIVENESS  AND  STABILITY         219 

The  quality  of  the  filter  paper  used  is  of  considerable  im- 
portance, and  the  committee  have  as  yet  been  unable  to  fix  a 
definite  specification,  but  suggest  the  following  tentatively : — 

(1)  To  consist  entirely  of  pure  normal  cotton  cellulose  of 
strongly  resistant  quality  and  free  from  any  loading  or  sizing. 

(2)  To  have  a  smooth  white  surface,  both  sides  being  as 
nearly  alike  as  possible. 

(3)  The  average  length  of  the  fibres  to  be  2  ±  -5  mm. 

(4)  The  thickness  to  be  i  '8  ±  '2  mm.  (Ciceri  Smith's  patent 
fixed  pressure  micrometer). 

(5)  The  last  treatment  in  its  preparation  to  be  a  thorough 
washing  with  distilled  water,  and  subsequent  air  drying  in 
a  pure  atmosphere. 

(6)  To  be  free  from  all  impurity,   particularly   acids, 
chlorine  and  peroxides. 

(7)  The  loss  of  weight  when  boiled  for  i  hour  with  3  per 
cent,  caustic  soda  solution  not  to  exceed  7-5  per  cent. 

(8)  It  is  not   to  produce  more  than   1*25  per  cent,  of 
its  weight  of  cuprous  oxide  when  heated  to  100°  C.  for 
15  minutes  with  Fehling's  solution  diluted  with  its  own 
volume  of  boiling  water. 

(9)  The  sheets  are  to  measure  50  cm.  by  15  cm.  and  are  to 
be  packed  in  hermetically  sealed  tin  cases  holding  100  sheets 
each. 

The  standard  tint  is  prepared  by  shaking  '48  gram  of 
finest  yellow  ochre,  *2  gram  raw  umber  and  5  grams  of 
fine  white  gum  arabic,  all  of  which  have  been  very  finely 
ground  in  an  agate  mortar,  with  100  c.c.  of  cold  water  until 
the  gum  is  dissolved.  After  standing  for  i  hour  a  stylo- 
graphic  pen  is  filled  from  the  centre  of  the  suspension,  and 
with  it  lines  not  less  than  *5  mm.  or  more  than  i  mm.  wide 
are  ruled  across  filter  paper. 

This  does  not  seem  a  very  satisfactory  method  of  pro- 
ducing a  standard  tint,  as  commercial  pigments  are  apt  to 
vary  in  shade,  but  a  sealed  pattern  is  kept  at  the  Home  Office 
with  which  comparisons  can  be  made. 

The  apparatus  for  carrying  out  the  heat  test  consists  of 
a  constant-level  copper  water-bath  with  seven  equally 


220  EXPLOSIVES 

spaced  holes  in  the  cover,  one  of  these  carrying  the  ther- 
mometer and  the  other  six  the  test-tubes  containing  the 
explosives  under  examination.  The  level  of  the  water  is 
J  in.  below  the  cover.  The  test-tubes  are  5^  in.  long,  and 
have  three  etched  marks  on  them  at  3  in.,  3§  in.  and  5  in. 
from  the  bottom  respectively.  The  lowest  of  these  indicates 
the  depth  the  tube  is  to  be  inserted  in  the  bath,  i.e.  until 
this  line  is  level  with  the  cover,  the  middle  one  indicates 
the  level  of  the  lower  moistened  part  of  the  test  paper  during 
the  test  and  the  top  line  the  level  of  the  lower  side  of  the 
rubber  cork.  In  carrying  out  the  test  the  explosive  is 
prepared  as  described  below  and  transferred  to  the  test-tube. 
A  piece  of  test  paper  is  then  impaled  on  a  platinum  hook 
sealed  on  to  a  glass  rod,  this  latter  passing  through  a  rubber 
cork,  and  the  upper  edge  of  the  paper  moistened  with  a 
mixture  of  equal  volumes  of  distilled  water  and  pure  glycerine 
(B.P.  specification).  The  rubber  cork  is  then  inserted  into 
the  test-tube,  and  the  whole  slipped  into  one  of  the  holes 
in  the  cover  of  the  water-bath  and  covered  with  an  opaque 
cap  to  exclude  light.  The  temperature  of  the  bath  is  160° 
Fahr.  or  170°  Fahr.,  depending  on  the  explosive  being  tested, 
and  the  time  is  noted  which  elapses  before  the  brown  line 
which  appears  at  the  margin  of  the  wet  and  dry  portions 
of  the  paper  matches  the  standard. 

When  setting  up  a  test  absolute  cleanliness  must  be 
observed,  and  on  no  account  must  the  paper  be  touched 
with  the  fingers,  forceps  being  used. 

In  preparing  explosives  for  the  test,  the  end  portions  of 
cartridges  or  sticks  are  always  rejected.  The  following 
outlines  the  methods  employed  for  the  different  types  of 
explosives : — 

I.  Dynamite  and  other  nitroglycerine  preparations  from 
which  the  nitroglycerine  can  be  conveniently  extracted  with 
water. 

Thirteen  grams  of  the  explosive  are  evenly  pressed  down 
with  a  glass  rod  on  a  filter  paper  supported  by  a  5j-cm. 
glass  funnel.  The  funnel  is  then  placed  in  a  heat  test-tube 
and  filled  with  water.  This  displaces  the  nitroglycerine  of 


SENSITIVENESS  AND  STABILITY         221 

which  2  c.c.  are  collected,  special  heat  test-tubes  with  a 
mark  corresponding  to  this  amount  being  used.  If  any 
water  goes  through  with  the  nitroglycerine  a  fresh  sample 
of  the  explosive  must  be  extracted. 

II.  Carbonite  and  similar  friable  preparations  from  which 
the  nitroglycerine  cannot  be  conveniently  extracted  with  water. 

A  sample  weighing  3*2  grams  is  transferred  to  the  heat 
test-tube  and  pressed  down  to  a  height  of  3  cm.  by  means 
of  a  flat-headed  glass  rod. 

III.  Cordite  and  other  Propellants  of  Class  3,  Division  i. 
If  the  explosive  is  in  sticks  or  tubes  these  are  wiped  with 
filter  paper,  the  ends  cut  off  and  rejected,  and  the  remainder 
then  cut  into  pieces  J  in.  long  and  ground  and  sieved,  a 
standard  grinding  mill  and  a  standard  nest  of  sieves  being 
specified  by  the  committee.     The  weight  of  the  ground  and 
sieved  sample  taken  for  the  test  is  i'6  grams,  this  not  being 
pressed  down  but  merely  made  to  settle  by  tapping  the 
outside  of  the  tube.     If  the  explosive  is  in  grains  it  is  not 
ground  or  sieved.     Nitrocellulose  propellants  when  in  sticks 
or  tubes  are  treated  in  the  same  way. 

IV.  Nitrocellulose  Pulp. 

The  explosive  is  pressed  between  six  thicknesses  of 
filter  paper,  and  5  grams  of  the  pressed  pulp  weighed  out 
and  dried  at  48*9°  C.  on  an  aluminium  tray  for  15  minutes. 
The  dried  sample  is  then  sieved  under  standard  conditions, 
exposed  to  the  air  for  4  hours,  and  then  1*3  grams  weighed 
out,  transferred  to  the  heat  test-tube  and  pressed  down 
gently  to  a  height  of  3  cm. 

Nitrocellulose  propellants  in  grains  are  tested  in  the 
same  way  as  guncotton  pulp,  except  that  they  are  not 
sieved  and  the  preliminary  pressing  between  filter  paper  is 
of  course  dispensed  with. 

V.  Compressed  Guncotton. 

Scrapings  are  taken  from  the  centre  of  the  slab  by  means 
of  a  horn  spatulum  and  stirred  for  15  minutes  with  cold 
distilled  water.  The  water  is  then  poured  off  and  the 
process  repeated,  after  which  the  guncotton  is  treated  in 
exactly  the  same  way  as  guncotton  pulp. 


222  EXPLOSIVES 

VI.  Bellite  and  Analogous  Preparations. 

The  weight  taken  is  1-3  grams,  and  this  is  gently  tapped 
to  the  bottom  of  the  test-tube. 

VII.  Gelatinized  Explosives. 

A  sample  weighing  3-2  grams  is  weighed  out  and  ground 
up  with  6*5  grams  of  French  chalk  in  a  Wedgwood  pestle  and 
mortar,  the  grinding  being  carried  out  at  first  with  a  squeez- 
ing and  then  with  a  circular  movement  of  the  pestle.  With 
Blasting  Gelatine  the  squeezing  movement  is  carried  on  for 
i  J  minutes,  with  Gelatine  Dynamite  for  i  minute,  and  with 
Gelignite  for  J  minute,  the  circular  movement  being  in  all 
cases  maintained  for  J  minute,  after  which  the  mass  should 
be  homogeneous  in  appearance.  The  mixture  is  gently 
pressed  down  in  the  heat  test-tube  to  a  height  of  5  cm. 

The  committee  found  that  different  qualities  of  French 
chalk  give  different  results  when  used  for  heat  test  purposes, 
but  they  were  unable  either  to  find  a  substitute  or  propose 
a  definite  specification.  As  a  tentative  measure  they  suggest 
the  following  : — 

(1)  It  must  not  contain  more  than  *5  per  cent,  of  moisture. 

(2)  Its  bulk  must  be  such  that  50  c.c.  without  ramming 
or  tapping  weigh  23*5  ±  i  gram. 

(3)  It  must  pass  a  sieve  composed  of  wire  '075  mm.  in 
diameter  and  having  6400  meshes  to  the  square  centimetre, 
no  rubbing  being  used. 

(4)  It  must  contain  less  than   'i   per  cent,  of  soluble 
alkali  calculated  as  CaCO3. 

(5)  When  warmed  with  hydrochloric  acid  it  must  give 
off  at  least  -25  per  cent,  of   carbon  dioxide,  but  not  more 
than  i  per  cent. 

(6)  It  must  not  absorb  more  than  -5  per  cent,  of  moisture 
when  exposed  for  24  hours  to  a  saturated  atmosphere  at 
I5°-20°  C.  after  being  dried  at  100°  C. 

Before  use  it  is  washed  with  distilled  water,  dried  at 
65°-70°  C.,  and  then  exposed  to  a  saturated  atmosphere  for 
24  hours.  This  cannot  be  said  to  be  a  satisfactory  definition, 
and  it  should  not  be  impossible  to  obtain  a  more  definite 
chemical  compound  suitable  for  the  purpose, 


SENSITIVENESS  AND  STABILITY         223 

The  following  table  shows  the  temperature  and  amount 
of  the  different  explosives  used,  together  with  the  minimum 
time  in  minutes  they  are  required  to  stand  : — 


Explosive. 

Quantity. 

Tempera- 
ture. 

Time. 

Nitroglycerine  extracted  from  Dynamite 
Friable  nitroglycerine  explosives 

2  C.C. 

3'  2  grams 

160°  F. 
160°  F. 

15 

7 

Gelatinized  explosives 

+6'5      ',',         \ 

1  60°  F. 

10 

French  chalk  j 

Cordite  and    other  nitroglycerine  pro- 

f^ 

pellants 

i  '6  grams 

160°  F. 

IO 

Nitrocellulose,  pulp  or  compressed 

1-3 

I70°F. 

10 

Nitrocellulose  propellants 
Bellite,  and  the  like         

1-3  ;; 

170°  F. 
170°  F. 

10 
10 

Cordite     Mark    I.    and    Cordite    M.D. 

(Government  Contracts) 

1-6      „ 

180°  F. 

30 

The  heat  test  has  been  adopted  by  most  countries  either 
alone  or,  more  usually,  in  conjunction  with  other  tests  as 
the  standard  method  of  measuring  stability,  but  the  details 
of  its  application  naturally  differ  in  some  respects  from 
those  in  force  in  Great  Britain.  It  would  be  a  great  con- 
venience if  an  international  method  of  carrying  out  the  test 
could  be  established  and  adopted  by  all  countries.  The 
test  suffers  from  the  disadvantages  of  being  too  sensitive, 
and  of  being  masked  by  minute  traces  of  certain  chemicals 
such  as  mercuric  chloride.  Alcohol  and  ethyl  acetate 
prolong  it,  and  consequently  it  is  not  very  reliable  for 
nitrocellulose  propellants  which  have  been  gelatinized  by 
these  solvents.  On  the  other  hand,  ozone  or  peroxide  if 
present  in  minute  traces  greatly  reduce  it,  and  so  does  oxalic 
acid,  although  it  probably  does  not  affect  the  real  stability. 

As  a  manufacturers'  guide  the  test  is  undoubtedly  useful, 
but  as  a  guarantee  of  stability  far  too  much  reliance  would 
seem  to  be  placed  on  it,  as  unless  a  very  careful  analysis  of 
the  explosive  is  made  at  the  same  time  it  is  quite  possible 
that  really  unstable  explosives  might  pass  the  test,  whereas 
really  stable  ones  might  fail.  The  test  is  really  too  sensitive, 
135  X  io~6  mgr.  of  nitrogen  peroxide  being  sufficient  to 
produce  the  standard  tint.  It*  is  difficult,  however,  to 


224  EXPLOSIVES 

propose  a  more  satisfactory  test,  although  several  attempts 
have  been  made  to  do  so.  These  may  be  divided  into  three 
broad  classes,  viz.  tests  similar  in  nature  to  the  Abel  heat 
test,  in  which  reliance  is  placed  on  the  detection  of  traces  of 
oxides  of  nitrogen ;  tests  in  which  the  explosive  is  submitted 
to  more  drastic  treatment  and  which  rely  on  the  production 
of  visible  fumes,  self -heating  or  explosion ;  and  quantitative 
tests,  in  which  the  quantity  of  oxides  of  nitrogen  is  actually 
measured.  Of  the  trace  tests  may  be  mentioned  the  Gutt- 
mann,  Spica  and  Moir  tests.  Of  these  the  first  relies  on  the 
production  of  colour  in  a  paper  impregnated  with  a  solution 
of  diphenylamine  and  dilute  sulphuric  acid.  It  is  not 
masked  by  mercuric  chloride  or  by  alcohol  or  ethyl  acetate, 
and  is  in  use  in  some  countries,  although  its  reliability  has 
been  criticized.  Spica's  test  is  similar,  except  that  m- 
phenylenediamine  and  cane  sugar  are  used,  but  it  is  far  too 
sensitive.  Moir's  test,  on  the  other  hand,  employs  a  mixture 
of  a-naphthylamine,  sulphanilic  acid  and  acetic  acid,  and 
is  even  more  sensitive. 

Vieille's  test  involves  more  drastic  treatment  of  the 
explosive,  and  a  much  less  sensitive  indicator  is  used,  viz. 
litmus  paper.  It  is  carried  out  by  heating  the  explosive 
on  successive  days  for  8  hours  to  110°  C.  or  until  the  test 
paper  assumes  the  standard  tint.  This  process  is  repeated 
daily  until  the  time  is  reduced  to  i  hour,  and  the  sum  of 
all  the  times  then  taken  as  a  measure  of  stability.  Although 
officially  adopted  in  France,  the  test  must  be  regarded  as 
a  very  crude  one. 

A  somewhat  more  satisfactory  test  of  a  similar  nature  is 
used  in  Germany.  In  this  test  the  explosive  is  heated  under 
standard  conditions  at  135°  C.  (the  boiling  point  of  xylol), 
and  the  time  noted  which  elapses  before  (i)  litmus  paper  is 
reddened  ;  (2)  brown  fumes  become  visible  ;  (3)  explosion 
takes  place.  If  many  samples  are  to  be  tested  it  is  a  some- 
what tiresome  test  to  carry  out  owing  to  the  explosion. 

Another  test  depending  on  the  production  of  brown  fumes 
has  been  introduced  for  testing  Mark  I.  Service  Cordite, 
which  has  been  in  stock  for  some  time,  and  the  heat  test 


SENSITIVENESS  AND  STABILITY         225 

of  which  has  fallen  to  between  four  and  eight  minutes  at 
160°  F.  The  test  is  applied  by  placing  50  grams  of  the 
ground  Cordite  in  a  vacuum- jacketed  silvered  flask  heated 
by  a  water-bath  to  80°  C.  A  sensitive  thermometer  is  in 
contact  with  the  Cordite,  and  the  neck  of  the  vessel  is 
provided  with  a  side  tube.  Observations  are  made  of  the 
interval  of  time  that  elapses  before  (i)  brown  fumes  are  seen 
in  the  side  tube  ;  (2)  the  Cordite  begins  to  heat  spontane- 
ously ;  (3)  the  spontaneous  rise  in  temperature  reaches  2°  C. 
The  test  is  known  as  the  Waltham  Abbey  Silvered  Vessel  Test. 

Of  the  quantitative  tests,  the  best  known  is  that  devised 
by  Will.  This  is  carried  out  by  heating  the  explosive  to 
135°  C.  in  a  current  of  pure  carbon  dioxide,  the  rate  of  flow 
of  the  gas  being  1000-1500  c.c.  per  hour.  The  carbon  dioxide 
and  gases  evolved  by  the  explosive  are  then  led  over 
heated  cupric  oxide  and  metallic  copper  in  order  to  oxidize 
any  organic  matter  and  to  reduce  oxides  of  nitrogen  to 
elementary  nitrogen.  Finally,  they  are  collected  over  40 
per  cent,  caustic  potash  in  order  to  absorb  the  carbon  dioxide. 
The  volume  of  nitrogen  thus  obtained  is  noted  at  regular 
intervals  during  the  test,  and  from  the  figures  thus  obtained 
a  very  good  idea  of  the  rate  of  decomposition  of  the  explosive 
can  be  formed. 

Other  tests  of  a  similar  nature  have  been  devised,  but 
they  present  little  if  any  advantage  over  the  Will  test. 

LITERATURE 
MECHANICAL  SHOCK 

A  friction  test  which  has  been  adopted  in  America  is  described  in  the 
Bulletin  of  the  U.S  Bureau  of  Mines,  No.  66,  pp.  15  and  290. 

The  falling  weight  test  is  described  in  the  following  publications  : — 

"  VI.  International  Congress  of  Applied  Chemistry,"  vol.  2,  p.  522. 

"  VII.  International  Congress  of  Applied  Chemistry,"  Section  III.,  p.  23. 

S.S.,  1906,  pp.  14,  209.  Bulletin  of  U.S.  Bureau  of  Mines,  No.  66, 
pp.  17,  287.  Marine- Rundschau,  1905,  1345. 

DETONATION  AND  INFLUENCE 

Z.  ang.,  1904,  546. 
P.S.,  1913,  p.  145. 

"  VH.  International  Congress  of  Applied  Chemistry,"  vol.  iii.  b,  p.  30. 
Bulletin  of  the  U.S.  Bureau  of  Mines,  No.  15. 
T.  15 


226  EXPLOSIVES 


EXUDATION 

U.S.  Bureau  of  Explosives  Reports,  Nos.  2  and  4. 
S.S.,  1910,  p.  213.     A.E.,  1914,  pp.  150,  162. 

INTERNATIONAL  COMMITTEE 

"  VIII.  International  Congress  of  Applied  Chemistry,"  vol.  25,  pp.  261, 
305. 

HEAT  TEST,  ETC. 

Very  full  directions  for  the  application  of  the  Heat  Test  will  be  found 
in  "  First  Report  of  the  Departmental  Committee  on  the  Heat  Test  as 
Applied  to  Explosives,"  published  by  Authority,  London,  1914.  This 
publication  gives  detailed  drawings  of  the  apparatus  required.  Some 
United  States  conditions  will  be  found  in  A.  Marshall,  "  Explosives," 
vol.  ii.,  London,  1917,  and  in  E.  C.  Worden,  "  Nitrocellulose  Industry," 
vol.  ii.,  London,  1911. 

Several  papers  describing  research  work  on  the  test  have  appeared 
from  time  to  time,  of  which  /. S.C.I.,  1910,  130,  is  of  particular  interest. 

Guttmann  described  his  test  in  J. S.C.I.,  1897,  293.     See  also  S.S.,  1912, 

P-  I53- 

Moir's  Test  and  Egerton's  modification  of  it  are  treated  in  J. S.C.I., 

1913.  33*.  and  J9*4»  Ir3- 

Vieille's  Test  is  described  by  R.  Escales  in  "  Schiessbaumwolle/'  p.  184, 
and  in  E.  C.  Worden,  "  Nitrocellulose  Industry,"  vol.  ii.  p.  969. 

The  best  descriptions  of  the  German  test  at  135°  C.  will  be  found  in 
R.  Escales  "  Schiessbaumwolle,"  p.  183,  and  in  E.  C.  Worden,  "  Nitro- 
cellulose Industry,"  p.  971. 

A.  Marshall  also  gives  a  short  description  of  it  in  his  book  "  Explosives," 
vol.  ii.  p.  662. 

The  Waltham  Abbey  Silvered  Vessel  Test  is  described  in  "  Regulations 
for  Army  Ordnance  Services,"  published  by  Authority  (1908). 

Will's  Quantitative  Test  has  been  studied  by  Robertson  in  J.S.C.I., 
1902,  819,  and  Soc.,  1907,  761.  Further  descriptions  of  the  test  will  be 
found  in — 

R.  Escales  "  Schiessbaumwolle,"  p.  186. 

E.  C.  Worden,  "  Nitrocellulose  Industry,"  p.  974. 

The  following  references  deal  with  other  tests  of  a  similar  nature  : — 

Z.  ang.,  1904,  982  ;  J. S.C.I.,  1905,  347  ;  1912,  161. 

/.  Am.  Chem.  Soc.,  30,  271  ;  Soc.,  1907,  764.  S.S.,  1905,  p.  29  ;  1910, 
p.  121.  P.S.,  xiv.  p.  42.  A.R.,  1903,26;  1904,28;  1905,  28.  "VIII. 
Congress  of  Applied  Chemistry,"  vol.  iii.  b,  pp.  147,  157.  Also  R.  Escales, 
"Schiessbaumwolle,"  pp.  177-198;  E.  C.  Worden,  "Nitrocellulose  In- 
dustry," pp.  968-984. 


CONCLUSION 

IN  surveying  the  ingredients  which  so  far  have  been  found 
suitable  for  use  in  the  manufacture  of  explosives,  one  is  at 
once  struck  by  the  paucity  of  the  number  of  oxidizing 
agents  available.  Of  organic  compounds  only  one,  viz. 
nitroglycerine,  contains  more  oxygen  than  is  necessary  for 
its  complete  oxidation.  It  is  true  that  one  or  two  compounds 
such  as  tetranitro  methane  contain  an  excess  of  oxygen, 
but  they  are  difficult  to  obtain,  and  even  if  obtained  have 
objectionable  qualities  such  as  intense  toxic  action.  Nitro- 
mannitol,  of  course,  has  some  available  oxygen,  but  it  is 
too  expensive  for  general  use,  and  other  possible  compounds 
such  as  dinitro  tartaric  acid  are  far  too  unstable.  As  it  is 
theoretically  impossible  to  obtain  a  nitroaromatic  hydro- 
carbon with  available  oxygen,  the  unknown  hexanitro- 
benzene  would  only  contain  just  enough  for  its  complete 
oxidation,  the  chances  of  obtaining  a  suitable  organic 
oxidizing  agent  would  seem  very  remote.  Of  the  inorganic 
oxidizing  agents  available,  only  three  classes  are  of  any 
importance,  viz.  the  nitrates,  chlorates  and  perchlorates, 
although  bichromates  have  been  used  to  a  very  minor 
extent. 

Of  these  the  nitrates  are  the  cheapest,  but  unfortunately 
the  most  suited  of  them,  viz.  ammonium  nitrate,  has  the 
objectionable  quality  of  being  very  hygroscopic.  In  spite 
of  this  it  has  met  with  wide  application,  and  is  probably 
destined  to  be  employed  to  a  far  greater  extent  in  the  near 
future  owing  to  the  production  of  cheap  ammonia  by  the 
Haber  process  and  of  cheap  nitric  acid  by  the  oxidation  of 
this  or  directly  from  the  air  by  electrical  means.  Up  to 


228  EXPLOSIVES 

the  present  waterproofing  the  cartridges  with  wax  has 
been  chiefly  relied  on  as  a  means  of  preventing  the  absorption 
of  water  by  the  explosive,  although  one  or  two  explosives 
are  put  up  in  cases  made  of  an  alloy  of  tin  and  lead.  These 
are  objectionable,  however,  in  underground  workings  owing 
to  the  poisonous  nature  of  the  lead  oxide  produced.  Possibly 
aluminium  foil  may  prove  more  suitable  as  its  oxide  is  not 
poisonous,  and  the  heat  of  combustion  of  the  foil  would 
considerably  increase  the  power  of  the  explosion.  It  should 
be  noted  that  ammonium  nitrate,  with  the  exception  of 
ammonium  perchlorate,  is  the  only  inorganic  oxidizing  agent 
giving  no  solid  products. 

Of  the  other  nitrates,  sodium  nitrate  is  the  cheapest,  but 
suffers  from  the  same  disadvantage  as  ammonium  nitrate, 
only  to  a  lesser  extent.  Potassium  nitrate  has  not  this 
disadvanatge,  but  is  much  higher  in  price.  Neither  barium 
nor  lead  nitrate  is  hygroscopic,  but  unfortunately  both 
barium  and  lead  salts  are  very  poisonous,  so  that  neither 
of  these  salts  is  suited  for  use  as  an  ingredient  in  explosives 
for  use  underground,  and  in  addition  to  its  toxic  properties, 
lead  nitrate  reduces  the  velocity  of  detonation  to  a  great 
extent.  As  a  class  the  nitrates,  and  particularly  those  of 
ammonium,  sodium,  and  potassium,  are  likely  to  hold  the 
premier  place  as  oxidizing  constituents  in  explosives.  In 
this  connection  it  should  be  pointed  out  that  the  synthetic 
nitric  acid  processes  are  at  present  more  suited  to  the 
production  of  nitrates  than  to  the  production  of  nitric  acid. 
In  all  these  processes  it  is  not  nitric  acid  but  nitric  dioxide 
that  is  produced,  and  although  this  can  be  converted  into 
nitric  acid  by  the  action  of  water  and  air — 

3NO2  +  H20  =  2HN03  +  NO 
NO  +  O  =  NO2 

this  can  only  be  done  at  present  by  means  of  an  elaborate 
system  of  towers,  the  gases  flowing  in  one  direction  and  the 
liquor  being  circulated  from  the  bottom  of  one  tower  to 
the  top  of  the  next  on  the  counter-current  principle.  Pump- 
ing straight  nitric  acid  is  always  troublesome,  and  although 


CONCLUSION  229 

it  can  be  achieved  with  ferro-silicon  pumps  or  in  glass  or 
stoneware  pipes  by  the  air-lift,  the  former  are  expensive 
and  the  latter  inefficient.  In  any  case,  the  towers  yield  an 
acid  of  a  strength  not  exceeding  60  per  cent.,  which  is  too 
weak  for  most  nitrations,  and  it  can  only  be  concentrated 
by  distillation  with  sulphuric  acid,  calcium  nitrate  or  other 
suitable  dehydrating  agent.  The  methods  of  concentration 
will  no  doubt  be  greatly  improved  in  the  near  future,  but 
in  the  meantime  the  weak  acid  is  quite  suitable  for  making 
nitrates,  as  it  is  only  necessary  to  neutralize  it  with  the  base 
and  then  evaporate  the  solution.  Of  course  only  a  small  pro- 
portion of  the  nitrate  made  will  be  used  for  the  production 
of  explosives,  the  bulk  being  manufactured  for  agricultural 
purposes.  It  may  be  remarked  in  passing  that  the  use  of 
synthetic  nitric  acid  will  go  a  long  way  towards  simplifying 
the  chemical  engineering  side  of  plant  construction,  as  the 
synthetic  acid,  unlike  that  obtained  from  Chili  saltpetre, 
contains  no  chlorine  and  is  consequently  much  less  corrosive. 
Probably  chrome  steel  will  be  found  quite  suitable  for 
handling  it,  although  this  alloy  is  badly  attacked  by 
commercial  nitric  acid  made  from  Chili  saltpetre. 

Of  the  chlorates,  only  the  potassium  salt  is  used  to  any 
extent,  the  sodium  salt  being  too  deliquescent  and  the 
ammonium  salt  unstable.  Even  the  potassium  salt  is 
never  likely  to  be  much  used  except  for  the  production  of 
matches,  as  Cheddite  is  about  the  only  chlorate  mixture 
which  is  not  unduly  sensitive,  or  likely  to  become  so  on 
keeping. 

The  perchlorates  are  more  stable  than  the  chlorates, 
from  which  they  are  obtained  by  electrolysis,  and  in  addition 
they  contain  more  oxygen.  Before  the  war  their  use  was 
on  the  increase,  and  the  erection  of  a  large  factory  for  their 
production  for  war  purposes  should  lead  to  their  increased 
application.  It  is  interesting  to  compare  the  prices  of 
nitrates,  chlorates  and  perchlorates,  and  the  following  figures 
for  the  potassium  salts  are  based  on  prices  current  in  1910. 
The  figures  are  in  shillings  per  100  Ibs.  of  salt  and  in  shillings 
per  Ib.  of  available  oxygen  : — 


230  EXPLOSIVES 


Price  per  cwt. 
Salt. 

Per  cent. 
Available 
Oxygen. 

Price  per  Ib. 
Available 
Oxygen. 

:'•; 

47 
66 
80 

40 
39'3 

46'3 

I-I7 

1-68 
173 

KN03 

KClOg 

KC1O4 

The  fact  that  the  perchlorate  is  slightly  more  expensive 
than  the  chlorate  per  unit  available  oxygen  is  more  than 
counterbalanced  by  increased  safety,  but  it  is  difficult  to 
see  how  perchlorates  can  ever  compete  with  nitrates  for 
general  purposes,  especially  in  view  of  the  production  of 
cheap  nitric  acid  in  the  near  future,  although  they  will  no 
doubt  be  increasingly  used  for  special  purposes.  Ammonium 
perchlorate,  like  ammonium  nitrate,  gives  no  solid  matter, 
but  unfortunately  it  gives  chlorine,  and  so  can  only  be  used 
in  conjunction  with  an  alkali  or  alkali  earth  nitrate  or  organic 
salt  to  provide  a  base  with  which  the  chlorine  can  combine. 
It  is  practically  non-hygroscopic,  and  cost  (pre-war)  about 
5f^.  per  Ib.,  this  corresponding  to  3*8  shillings  per  Ib. 
of  available  oxygen.  This  figure  must  not  be  compared 
with  those  given  above  for  the  potassium  salts  as  ammonium 
perchlorate  is  an  explosive  in  itself — 

2NH4C104  =  4H20  +  C12  +  N2  +  2O2 

In  spite  of  the  disadvantage  of  producing  chlorine  the 
salt  is  likely  to  find  considerable  application,  as  it  seems  to 
assist  the  detonation  to  spread  provided  a  strong  enough 
detonator  or  primer  is  used. 

Turning  now  to  the  combustible  matters,  these  are 
chiefly  nitroaromatic  hydrocarbons,  and  to  produce  a  really 
satisfactory  explosive  they  should  for  preference  be  capable 
of  exploding  alone.  At  present  the  nitro  derivatives  of 
benzole  and  toluol  are  chiefly  used,  and  to  a  lesser  extent 
the  nitro  derivatives  of  naphthalene.  This  latter  hydro- 
carbon, like  all  condensed  nuclei  compounds,  suffers  from  the 
disadvantage  that  the  number  of  nitro  groups  that  can  be 
introduced  is  smaller  in  proportion  to  the  number  of  carbon 
atoms  than  is  the  case  with  uncondensed  nuclei,  and  for 
this  reason  derivatives  of  fluorene,  acenaphthene,  pyrene,  etc., 


CONCLUSION 


231 


although  they  will  probably  come  into  use  in  the  dye  stuff 
industry,  are  not  likely  to  be  employed  in  the  manufacture 
of  explosives  even  if  produced  at  a  sufficiently  low  price. 
This  is  made  clear  in  the  following  table,  in  which  is  shown 
the  number  of  atoms  of  oxygen  per  molecule  of  compound 
and  the  grams  of  oxygen  per  hundred  grams  of  compound 
which  are  necessary  for  complete  oxidation  : — 


Extra  Oxygen  required. 

Molecular 

weight. 

_ 

Atoms  per  mol.       jo^Tg^ms. 

Dinitrobenzole 

168 

10                     94*4 

Trinitrobenzole 

213 

?i                   56'4 

Dinitrotoluol 

182 

I3                   II4 

Trinitrotoluol 

227 

Ioi                  74 

Trinitronaphthalene     .  . 
Tetranitronaphthalene 

263 

308 

i6£                 loo 
16                     83-1 

Trinitrobenzole  shows  up  best,  but  unfortunately  it  is 
too  expensive  to  produce.  It  is  notable  that  no  catalyst 
for  facilitating  nitration  has  yet  been  discovered.  Such  a 
catalyst  would  be  most  valuable,  and  might  have  a  great 
influence  on  explosives  manufacture. 

It  seems  improbable  that  for  general  purposes  much 
progress  is  to  be  expected  in  the  way  of  production  of  new 
combustible  matters,  although  exhaustive  nitration  may, 
and  probably  will,  lead  to  the  production  of  highly  nitrated 
compounds  like  tetryl  which,  although  suitable  for  special 
purposes  such  as  for  initiators,  are  too  expensive  for  general 
blasting  use.  The  numerous  trinitrotoluol  plants  put  down 
for  war  purposes  and  the  experience  gained  in  the  manu- 
facture of  this  substance  render  it  probable  that  it  will 
become  the  standard  combustible.  In  any  case,  the  amount 
held  in  stock  for  military  purposes  will  probably  suffice  to 
supply  the  needs  of  the  explosives  works  for  some  time  if  it 
is  disposed  of  as  "  surplus  stores." 

Up  to  the  present  Gelignite  has  been  the  standard  high 
explosive  for  general  blasting  purposes,  and  nitroglycerine 
explosives  have  also  been  very  widely  used  in  coal  mines, 
but  it  is  doubtful  if  nitroglycerine  explosives  will  retain  their 


232  EXPLOSIVES 

supremacy  much  longer.  The  production  of  cheap  ammo- 
nium nitrate  and  cheap  T.N.T.  will  certainly  give  a  great 
impetus  to  explosive  mixtures  composed  of  these  ingredients, 
and  as  their  manufacture  is  cheap  and  safe  so  that  very 
little  explosion  risk  has  to  be  carried  it  should  be  possible 
to  put  them  on  the  market  at  a  very  low  price,  thus  enabling 
their  use  to  become  more  general,  e.g.  for  agricultural  work. 
Whether  the  Merger  Company  (Explosives  Traders,  Ltd.) 
which  now  controls  practically  the  whole  explosives  trade 
in  Great  Britain  will  do  so  or  not  remains  to  be  seen.  If 
not  it  is  probable  that  the  big  mine  owners  will  manufacture 
their  own  explosives,  more  especially  as  the  big  coal  mine 
companies  usually  also  own  by-product  coke  oven  in- 
stallations, and  will  no  doubt  be  among  the  first  to  instal 
synthetic  ammonia  plants.  Mixtures  of  T.N.T.  and  am- 
monium nitrate  can  be  made  up  to  be  as  powerful  as  Gelig- 
nite, and  by  adding  aluminium  powder  extremely  powerful 
explosives  of  the  Ammonal  class  can  be  obtained.  Of 
course  there  is  always  the  difficulty  of  deliquescence,  but 
the  present  waxed  paper  wrappers  are  more  or  less  satis- 
factory and  are  capable  of  improvement,  and  the  introduction 
of  aluminium  foil  cases  would  seem  to  be  quite  feasible. 

The  future  is  likely  to  see  considerable  improvement  in 
detonators,  and  probably  the  ordinary  fulminate-chlorate 
detonator  will  be  very  largely  replaced  by  the  composite 
detonator  made  with  lead  azide,  unless  further  research 
brings  to  light  a  more  satisfactory  initiator. 

The  probable  development  of  the  propellant  branch  of  the 
industry  is  more  difficult  to  forecast,  although  minor  improve- 
ments will  be  brought  about  in  manufacturing  details.  No 
great  departure  from  present  day  composition  is  to  be  looked 
for  until  some  smokeless  oxidized  agent  is  discovered  which 
has  suitable  properties.  Of  the  only  two  available  at  present, 
ammonium  nitrate  is  far  too  deliquescent,  and  ammonium 
perchlorate  corrodes  the  barrel  too  much  to  be  used.  Unless 
such  an  oxidizing  agent  is  found  any  great  departure  from 
present  day  compositions  could  only  be  made  by  the  intro- 
duction of  some  "  combustible  matter  "  containing  sufficient 


CONCLUSION  233 

oxygen  to  explode  without  the  production  of  smoke,  i.e.  con- 
taining enough  oxygen  to  convert  the  hydrogen  into  water 
and  the  carbon  into  monoxide.  Both  trinitrobenzene  and 
tetryl  almost  satisfy  these  conditions,  and  an  almost  smoke- 
less powder  could  be  produced  from  them  by  adding  a  little 
potassium  nitrate.  Unfortunately  such  mixtures  are  far 
too  brisant  for  use  as  propellants,  and  at  present  it  is  not 
easy  to  see  how  their  combustion  is  to  be  regulated.  A 
propellant  made  from  definite  pure  chemical  compounds 
would  have  many  advantages  over  those  composed  of 
indeterminate  mixtures  like  nitrocellulose,  but  no  success 
has  yet  been  achieved  in  this  direction.  Of  course,  nitro 
starch  may  become  a  commercial  success,  but  it  is  little 
more  definite  in  nature  than  nitrocellulose. 

In  recent  years  a  considerable  number  of  patents  have 
been  taken  out  covering  the  use  of  stabilizers,  and  more 
progress  is  to  be  looked  for  in  this  direction,  a  stabilizer 
being  desired  which  does  not  have  a  bad  effect  on  the 
ballistic  properties  of  the  propellant  and  which  does  not 
mask  stability  tests,  thus  giving  rise  to  a  false  belief  in 
security. 

The  war  has  shown  to  what  an  extent  the  dyestuffs, 
explosives  and  fertilizer  trades  are  interdependent,  and  the 
advent  of  synthetic  nitrates  will  make  them  even  more  so. 
It  is  notable  that  one  of  the  largest  explosive  producers  in 
the  world,  B.  A.  du  Pont  de  Nemours  (U.S.A.),  is  now 
concentrating  on  synthetic  dyestuffs,  and  that  in  this  country 
Nobel's  Explosives  Company,  L,td.,  now  merged  into  Ex- 
plosives Trades,  lytd.,  have  acquired  a  large  interest  in  the 
dyestuff  combine.  Whether  this  tendency  to  concentrate 
business  in  the  hands  of  one  combine  will  ultimately  benefit 
the  consumer  or  not  is  doubtful,  although  it  will  no  doubt 
benefit  the  shareholders. 


INDEX 


A  I  MONOBEL,   134 

A  2  Monobel,  134 
Abel,  3,  137 

heat  test,  208,  217-224 

process,  3,  45 
Abelite  No.  i,  132,  133 

No.  4,  131 
Accidents,  9 
Acetic  acid,  88 

Ether.     See  Ethyl  acetate. 
Acetone,  74,  85,  88 

recovery,  77,  78 
Adler-Marke,  87 
After-flame,  119 

ratio,  118,  119 

separation,  34,  35 
Ageing,  84 
Ajax  powder,  137 
Alcohol,  87,  88 

-ether.     See  Ether-alcohol. 
Alcoholizing,  52 
Aldehyde,  88 
Aldorfit,  189,  195 
Alum,  164 
Aluminium  powder,    112-114,    176, 

177 

Amberite,  86 
Ammonal,  114,  195,  232 
Ammon-Carbonite,  118,  194 
Ammonia  Dynamite,  98,  191,  192 
Ammonite,  133 

No.  i,  127,  131,  133 

No.  4,  131,  133 

No.  5,  127,  133 
Ammonium  bichromate,  31,  86,  87 

chloride,  120,  131 

nitrate,  4,   11,   12,  31,  92,  97, 
98,  113-115,  199,  228,  232 

oxalate,  132 

perchlorate,   31,   92,    106,    107, 
112,  113 

phosphate,  164 

picrate  ,211 

Ammunition,  Definition  of,  13 
Amyl  acetate,  82 

alcohol,  81 
Anchorite,  132,  133 


Antimony  sulphide,  162 
Arkite,  No.  2,  136 
Astralite,  113,  211 
Atlas  Powder,  97 
Auer  Metal  No.  2,  170 
Axite,  78 
Azides,  28,  146 

|  BACK-FLASH,  69 
Bacon,  Roger,  1 
Ballistic  pendulum,  182-184 
!  Ballistite,  5,  72 
i  Barium  chlorate,  106 

cuprothiosulphate,  167 

nitrate,  82-86,  92,  228 

perchlorate,  92,  106 

sulphate,  94 
Barriers,  8 

Bashforth  chronograph,  204,  205 
Bellite  No.  i,  132,  133 

No.  2,  132,  133 

No.  4,  132,  133 
Bengal  Fire,  170-172 
Benzene  ozonide,  31 
Berthelot,  197 
Bichel,  118,  196,  197 

recorder,  196 

Black  powder.     See  Gunpowder. 
Blastine,  112 
Blasting  explosives,  90-116 

Gelatine,  4,  9,  10,  91,  104,  118, 
181,  182,  186,  194,  199,208, 
210 

Blending,  24,  76,  84 
Bobbinite,  26,  119,  137,  138 
Boiling  nitrocellulose,  50 
Bomb  calorimeter,  197-200 
|  Borax,  137 
Braun,  3 
Brick  dust,  93 
j  Briquets,  168 
Brisance  meter,  184 
Britonite  No.  2,  135,  136 

No.  3,  135,  136 
Buildings,  7 
Bulk  powders,  82-87 
Butylene,  42 


236 


INDEX 


CALCIUM  phosphide,  177 

silicide,  114 
Calorimetry,  197-200 
Cambrite,  135 
Cap  composition,  147-149 
Caps,   Percussion.     See   Percussion 

caps. 

Carbo-Dynamite,  97 
Carbonite,  98,  194,  199,  221 

No.  2,  211 
Cartridge   machines,    94,    95,    101, 

102,  115 

Castor  oil,  106,  112 
Catherine  wheels,  170,  174 
Cellulose    nitrate.     See  Nitrocellu- 
lose; Guncotton;  Collodion. 
Centrifugal  nitrator,  48 
Cerium  alloys,  168-170 

chloride,  169 

fluoride,  169 
Chancel,  162 
Charcoal,  18,  97 
Charge  limite,  122 
Cheddite,  6,  10,  31,   106,  109-113, 

189,  210 
Chlorate  explosives,  2,  5,  106-113 

mixture,  Definition  of,  12 

mixtures,  2,  5,  106-113 
Chlorates,  31,  106 
Chronograph,  202-205 
Classification,  10-15 
Coal  Mine  Explosives,  117-142 
Cocoa  powder,  18 
Colliery  Steelite,  111 
Collodion    cotton,    48,    49,    79-86, 

211,  221 

Coloured  fire.     See  Bengal  Fire. 
Composite  detonators,  154 
Condensed  powders,  82 
Coolers,  120,  130,  131 
Copper    ammonium     thiosulphate, 
147,  148 

sulphate,  26,  138 

thiocyanate,  163 
Cordite,  5,  71,  72-77,  221,  223 
Cork  dust,  108 
Corning,  2,  23 
Cotton,  44 
Crackers,  170 
Crusher  gauge,  195.  196 

DAHMENIT,  139 
Definition  of  explosive,  6 
Delayed  action  fuze,  159 
Deliquescence,  214,  215 
Denaby  Powder,  132 
Denitration,  64-66 
Densite  No.  3,  140 
No.  4,  140 


Deposit  of  washings,  37 

Deterrents,  70 

Detonating  fuze,  158,  159,  187,  193 

Detonation,  143,  211 

Detonator,  Definition  of,  13 

Detonators,  153-156 

Heat  of  explosion  of,  198 
Devine,  4 

Diazobenzene  nitrate,  30,  147 
Dieprez  Chronograph,  204,  205 
Diglycerine,  40,  41 
Dinitro  acetyl  glycerine,  41,  103 

benzole,  29,  52,  85,   185,   193, 
210,  231 

chlorbenzole,  59 

chlorhydrin,  28,  40,  103,  139 

diphenylamine,  63 

formin,  41,  103,  104 

glycerine,  40,  103,  139,  210 

glycol,  28,  29,  41.  43,  103 

naphthalene,  30 

phenol,  59 

tartaric  acid,  28 

toluol,  30,  52,  56,  85,  109,  193, 

194,  231 

Diphenylamine,  30,  71,  78,  81 
Direct  dipping  process,  45 
Displacement  process,  45 
Donarite,  118,  194,  211 
Dorfit  No.  i,  139 

No.  2,  139 

Dreadnaught  Powder,  133 
Drowning  tanks,  32,  35 
Drying  Cordite,  76,  77,  78 

cotton,  45 

fulminate,  146 

gunpowder,  24 

nitrocellulose,  51 

propellants,  76,  84 
Du  Pont  Permissible  No.  I,  134 
Dusting,  24 
Duxite,  136 

Dynamite,   96,   97,    191,    192,    194, 
220,  221 

No.  i,  9,  10,  93-96,  118,  181, 
194,  199,  210 

No.  2,  96 

No.  3,  97 

No.  4,  105 

No.  5,  105 

American,  96-98 

antrigrisouteuse,  140 

gelatinee,  105 

pump,  94,  95 
Dynammon,  139 
Dynobel,  137 

No.  2,  135 

No.  3,  135 

No.  4,  135 


INDEX 


237 


E.G.  POWDER,  6,  86 
Electric  detonators,  155,  156 
Erosion,  71 
Ether,  74,  81 

-alcohol,  44,  73,  74,  80,  81,  85 
Ethyl  acetate,  85,  87 
Expedite,  132,  133 
Explosif  Oa,  111 

O8,  108 

04,  111 

05,  111 

N  i  a  bis  couche,  141 

N  ib  bis  roche,  141 

N  ic  bis  roche,  141 

N  2  roche,  141 

N  3  roche,  141 

N  4  couche,  141 

type  P,  109,  110 
S,  109,  110 
41,  111,  210 
60,  111,  210 
6o«,  109,  110 
Explosifs  antigrisouteuses,  121,  141 

couches,  122,  141 

de  surete,  121,  141 

roches,  122,  141 

S.G.P.,  121 
Explosive  compounds,  28-66 

Definition  ot,  6 
Explosives  Act,  6 
Extra-Carbonite,  194 
Exudation,  104,  215 

FALLING  weight  test,  209,  210 
Fasan  Powder,  87 
Favier,  4,  113 

2  bis,  140 

explosives,  113 
Ferrosilicon,  114 
Filite,  78 

Filter-house,  35,  36 
Firework  composition,  14 

Definition  of,  14 
Fireworks,  170-177 
Flame,  118-120 
Flash  lights,  176,  177 
Frursheim,  6,  59 
Forcite  extra,  105 

superieure,  105 

No.  i,  105 
Forsyth,  2 
Fouling,  69 
Fractorite  B,  140 
French  chalk,  222 
Friction  test,  208,  209,  216 
Fulmenit,  113 
Fulminate.    See  Mercury  fulminate. 

Definition  of,  13 
Fu7c,  Definition  of,  13 


Fuze,  Detonating,  158 
Instantaneous,  158 
Safety,  156 
Shell,  2,  159,  160 


GALLERIES,  6,  118-125 
Gelatine  Carbonit,  139 

Dynamite,  4,  10,  104,  105,  182, 
191,  192,  208,  210 

Wetterastralit  I,  139 
Gelatinee,  105 

iB,  105 

Gelignite,  4,  9,  10,  91,  104,  105,  118, 
181,     182,    191,    192,     194,     199, 
208 
Gesteins-Dorfit,  195 

Westfalit,  114 
Glass  powder,  147 
Glazing,  24 
Glycerine,  31,  42 

dinitrate.  See  Dinitroglycerine. 

trinitrate.   See  Nitroglycerine. 
Glycol,  28,  43 

dinitrate.    See  Dinitroglycol. 
Glucose  nitrate.     See  Nitroglucose. 
Gomme  extraforte,  105 

B,  105 

3B,  105 

G,  105 

Granulating,  2,  23,  82,  83 
Graphite,  24,  72,  85 
Greek  Fire,  1 
Grinding,  19 
Grisounite  couche,  141 

roche,  128,  141 
Grisoutite,  140 

Guncotton,  2,  3,  45,  73,  193,  211, 221 
Gunpowder,   1,  10,   11,  17-27,   118, 

199,  210 
Guttmann's  test,  224 


HEAT  of  explosion,  119,  197,  213 

test,  11,  12,  208,  217-224 
Hercules  Powder,  97,  98 
Herculite,  137 
Herz,  147 

Hexanitro  benzene,  30 
diphenyl,  63 

amine,    30,    82,    63, 

193,  210 
oxide,  63 
sulphide,  63 
sulphone,  63 
inosite,  29 
mannitol,  28,  29,  62 
oxanilide,  63 
Holme's  Buoys,  170,  177 


INDEX 


"  IENA  "  disaster,  81 
Ignition,  213,  214 
Imperial  Schultze,  80 
Impregnating,  163,  164 
Incorporation,  20,  74,  214 
Indurite,  82 
Influence,  212 
Initiators,  143-156 
Inosite,  29 

nitrate,  29 

Instantaneous  fuze,  158 
Italian  powders,  78 


JELLYBAG  mixer,  149 
Judson  Powder,  98 

KENTITE,  132 
Kiesselguhr,  93 
Klepsydra,  204 
Kohlencarbonite,  140 
Kynarkite,  135 
Kynoch's  Smokeless,  86 

LABYRINTHS,  37 

Le  Boulange  Chronograph,  202-204 

Le  Chatelier,  201 

Lead  azide,  13,  28,  31,  143,  146,  147 

block,  179-181 

dioxide,  163 

nitrate,  92,  175,  228 

picrate,  147,  210 

thiocyanate,  163 

thiosulphate,  148 
Leaders,  176 
Liberti  disaster,  81 
Life-saving  rocket,  175 
Ligdyn,  98 
Lighting  buildings,  8 
Liquid  air,  4,  108 
Low  powder,  98 
Lyddite,  6 


MACARITE,  185,  193 

Magazines,  7 

Magnesium  powder,  176,  177 

sulphate,  120,  164 
Mahieu  Chronograph,  205 
Mallard,  201 

Manganese  dioxide,  108,  163 
Mannitol  hexanitrate.     See  Hexa- 

nitromannitol. 
Manufactured  Firework,  Definition 

of,  14 

Marcel  Chronograph,  204,  205 
Maroons,  170 
Match  composition,  163-167 


Match  machines,  164,  165 

Non-safety,  163 

Quick,  158,  176 

Safety,  163 

Slow,  158,  175 

Strike-anywhere,  163 

Wait-a-minute,  164 
Matches,  162-167 
McNab,  6,  120 

McRoberts  machine,  100,  101 
Mechanical  shock,  208,  209,  216 
Melinite,  6 
Mercury  chloride,  223 

fulminate,  2,  13,  28,  31,   143- 

146,  193,  199,  210 
Mettegang,  186,  197 

recorder,  186 
Mica,  96 
Milling,  20 

Mineral  jelly,  71,  73,  74 
Minite,  140 
Mixing  explosives,  19 
Moddite,  78,  79 
Moir's  test,  224 
Monobel  No.  i,  134 
Ai,  134 
A2,  134 

Mononitro.  See  under  Nitro. 
Mortar,  181 

Moulded  powders,  25,  67,  68 
Moulding,  25 
Mullerite,  87 
Muzzle  flame,  70 

velocity,  202 


NAPHTHA,  108 
Nathan,  37,  45 
Nationalite  No.  i,  132,  133 

No.  2,  132,  133 
Necrosis,  163 
Neonal,  137 

No.  i,  137 
Neu-Westfalit,  138 
Nitrate  Mixture,  Definition  of,  11 
Nitrating-centrifuge,  48,  49 

-house,  32,  37 
Nitrator-separator,  37-39 
Nitric  acid  recovery,  64,  65 
Nitro    acetin.       See    Dinitroacetyt 

glycerine, 
benzole,  82,  108 
benzyl  nitrate,  30 
cellulose,    23,   43,    44,    70,    82, 
211,     213,     221,    223.      See 
also   Collodion ;  Guncotton  ; 
Pyroxylin. 

chlorhydrin.    See  Dinitrochlor- 
hydrin. 


INDEX 


239 


Nitro  compound,  Definition  of,  11 
cotton.     See  Nitrocellulose, 
diazobenzene  nitrate,  30 
diglycerine.       See    Tetranitro- 

diglycerine. 

formin.   See  Dinitroformin. 
glucose,  29 
glycerine,  2,  3,  12,  28,  29,  37- 

41,   181,  191,   193,  199,  210, 

213,  223 

glycol.    See  Dinitroglycol. 
lignine,  5,  85 
mannitol.         See     Hexanitro- 

mannitol. 

methane,  29,  61,  62,  103 
naphthalene,  109,  111 
phenyl  nitromethane,  30 
starch,  29,  62 
sucrose,  29 
sugars,  29,  62 
toluol,  53 
Nobel,  3.  71,  195,  197 

OCHRE,  93 
Oleum,  32,  47,  53 
Oxyliquit,  108 
Ozonides,  31 

PACKING,  126,  155 
Paraffin,  109,  113 
Pendulum,  182-184 
Pentanitromethyl  aniline,  61 
Perchlorate  explosives,  111-113,  137 
Percussion  cap,  Definition  of,  14 

caps,  144-160 

fuzes,  160 

Permissible  explosives,  10,  121,  123 
Permitted  explosives,  10,  121,  123 
Permonite,  111,  195 

S.G.P.,140 
Pernitral,  112 
Peroxides,  31 
Peteval,  197 
Phosphoric  acid,  164 
Phosphorus,  162,  163 

Red,  163 

Scarlet,  163,  166 

sulphide,  163 

White,  162,  163,  166 
Phosy-iaw,  163 

Photographic  flash  lights,  176,  177 
Picric  acid,  5,  6,  30,  58,  59,   185, 
189,  190,  193,  211 

anhydride,  63 
Picryl  chloride,  63,  193 

sulphide,  63 
Pitite  No.  2,  135,  136 
Polarite,  111 
Porosity,  79 


Potassium  bichromate,  86,  87,  163 

chlorate,  92,  106-113,  162-167, 
230 

chloride,  134 

nitrate,  17,  18,  82-86,  92,  96- 
141,  230 

perchlorate,  92,  106,  107,  111- 

113,  137,  230 
Poudre  B,  5,  71,  81 

J,  86,  87 

M,  86,  87 

S,  86,  87 

T,  86,  87 

T  bis,  87 

Power  of  explosives,  178-184 
Pressing  caps,  152 

cordite,  74-76 

detonators,  154 

gunpowder,  21 

propellants,  74-76,  81 
Pressure  of  explosion,  67,  195 
Pre-washing,  36,  37 
Products  of  explosion,  26,  27,  91 
Promethee,  108 
Propellants  for  rifled  arms,  67-81 

Gunpowder,  19,  25 

Shot-gun,  82-87 

Smokeless,  67-89 

Nitrocellulose,   71,    72,    79-87, 
223 

Nitroglycerine,  70-79,  223 
Pulping  nitrocellulose,  51 
Pyrophoric  alloys,  168-170 
Pyrotechny,  170-177 
Pyroxylin,  50 

QUICK-MATCH,  158,  176 

RACK-A-ROCK,  4,  108 
Randanite,  96 
Recovery  of  acetone,  77 

alcohol,  81,  84,  145 

ether,  81,  84 

nitric  acid,  64,  65 

sulphuric  acid,  64-66 
Rex  Powder,  134 
Rintoul,  37 
Roburite  No.  4,  132 
Rockets,  170,  174,  175 
Rodman  gauge,  195 
Rohrenpulver,  78 
Roman  candles,  170,  174 
Rotherham  test,  123-125 
Rothweil  Powder,  87 

SABUMTE,  114 

antigrisouteuse,  141 
Safety,  7 

explosives,  117-141 


240 


INDEX 


Safety  fuze,  156 

Definition  of,  14 

Nitro,  98 
Saltpetre.     See  Potassium    nitrate 

and  Sodium  nitrate. 
Samsonite  No.  2,  132,  137 

No.  3,  137 
Sarrau,  197 
Saxonia,  87 
Schonbein,  2 
Schultze  Chronograph,  204,  205 

Cube  Powder,  86 

Powder,  5,  85,  86 
Sensitiveness,  207 
Separating-house,  34 
Separation,  34,  35,  37 
Shaking  test,  214 
Shell  fuzes,  159,  160 
Shells,  Pyrotechnic,  171 
Shot-gun  propellants,  82-87 
Silesia  No.  4,  111 
Silica,  35,  96 
Silk,  Artificial,  46 
Silvered  vessel  test,  224,  225 
Slow-match,  158,  175 
Smokeless  Diamond,  85 

propellants,  67-89 
Sobrero,  2 
Sodamide,  146 
Sodium  azide,  146 

chlorate,  92,  106,  109-111 

chloride,  11,  12,  132-134 

fluoride,  35 

nitrate,  11,  12,  92 
powders,  17,  25 

perchlorate,  92 

phosphate,  164 

tungstate,  164 
Solenite,  78 
Solvents,  87 

Specific  heats  of  gases,  201 
Spent  acid.   See  Waste  acid. 
Spica's  test,  224 
Sporting  Ballistite,  86 

propellants,  67-86 
Sprengel  explosives,  4,  5,  108,  109 
Sprengsalpeter,  25 
Squibs,  171,  173 
Stability,  207 
Stabilizers,  70,  233 
Stamp  mills,  20 
Stanford  Powder,  131 
Star  shell,  172,  173 
Starch  nitrates,  29,  62 
Stars,  Pyrotechnic,  170,  172,  173 
Statistics,  9 
Steelite,  111 
Stomonal  No.  i,  134 

No.  2,  134 


Stonite,  98 
Stoving,  24 
Straight  Dynamite,  97,  122,  191, 

192,  215 
Street,  5 

Stump  Powder,  98 
Sucrose  nitrate.    See  Nitrosucrose. 
Sulphur,  18 
Sunderite,  131 
Super-Curtisite,  132 

-Excellite,  134 

No.  2,  126,  134 

-Kolax,  135 
No.  2,  135 

-Rippite,  6,  136,  137 
Swale  Powder,  137 

TEMPERATURE  of  explosion,  200,  201 

ignition,  213 
Tetranitro  aniline,  6,  30,  59 

diglycerine,  28,  40,  103 

methane,  29,  62 

methyl  aniline,  6,  30,  60,  185, 
193,  210,  233 

methyl  phenyl  nitramine,  61 

naphthalene,  30,  231 

toluol,  30 

Tetryl.     See  Tetranitromethyl  ani- 
line. 

Thames  Powder  No.  2,  134 
Thawing  explosives,  90 
Thiophosphites,  167 
Thomson,  37,  45 
Thunderite,  118,  195,  199 
Tiger  Powder,  87 
Time  fuzes,  160 

recorder,  186 
Tin  thiocyanate,  163 
Tipping  matches,  164,  165 
Tonite,  115 
Touch  paper,  175 
Trauzl  test,  179-181 
Tremonite  S.  II.,  139 
Trinitro  benzole,  30,  193,  231,  233 

chlorbenzole.  See  Picryl  chlo- 
ride. 

cresol,  30,  193 

naphthalene,  30,  210,  231 

phenol.    See  Picric  acid. 

phenyl  methyl  nitramine,  30, 

60,  185,  193 
nitromethane,  30 

toluol,  6,  30,  52-58,  85,  99, 
103,  158,  159,  185,  189,  190, 
193,  194,  210,  211,  231 

xylol,  30 

Triolite.    See  Trinitrotoluol. 
Triplex  Safety  Glass,  149,  151 
Tritol.     See  Trinitrotoluol. 


INDEX 


241 


Trotyl.     See  Trinitrotoluol. 
Tubular  powders,  74 
Turpentine,  108 
Tutol  No.  2,  131 

UNITED    States    Military    Powder, 
79-81 

VARNISHING  caps,  152 
Vaseline.    See  Mineral  jelly. 
Velocity   of   detonation,    109,    110, 

118,  185-195,  212,  213 
Very  Stars,  170 
Victor  Powder,  132,  134,  135 

No.  2,  134,  135 
Vieille,  5,  71 
test,  224 
Viking  Powder  No.  I,  134 

No.  2,  134,  135 
Violence.     See  Brisance. 
Viscosity,  49 
Volkmann,  5 
von  Lenk,  2 
Vulcan  Powder,  98 

WALSRODE  Powder,  87 
Waltham    Abbey    Silvered    Vessel 
Test,  224,  225 


Warming  pans,  90 
Wash  house,  35,  36 

waters,  37,  145 
Washing  nitrocellulose,  50-52 

nitroglycerine,  35,  36 
Waste  acid,  34,  37,  47,  55,  64-66 
Waterproofing  cartridges,  127 
Werner  and  Pfleiderer  Machine,  74, 

75,  80,  94,  100 
Westialite  No.  3,  133 

fur  Kohle,  113 
Wetter-Dynamit,  194 

Dynammon,  139 

Fulmenit,  138 

Wettersichere  Sprengstoffe,  121,  138 
Whistling  fireworks,  174 
Will  test,  225 
Wood,  Carbonization  of,  18 

Nitration  of,  85,  86 
Wrappers,  91,  127-129,  136 
Wiirfelpulver,  78 

YONCKITE,   112 

10  bis,  140 

ZINC  sulphate,  164 
sulphide,  163 
thiophosphate,  167 


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T. 


16 


INDUSTRIAL    CHEMISTRY 

Being  a  Series  of  Volumes  Giving  a  Comprehensive  Survey  of 

THE    CHEMICAL    INDUSTRIES 

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